When Costco customers see the red and black Kirkland Signature label, they know they’re going to get a good product at a great price. But they don’t always know who’s making it.

Store brand products like Kirkland are typically manufactured by third parties, not the store itself. Many of these behind-the-scenes companies are actually famous retail titans, so you can save big on your grocery bill without losing quality.

While plenty of the names behind Kirkland Signature products are public knowledge — some printed right on the box — others remain a closely guarded secret. More than a few rumors have popped up from people claiming to be in the know.

Here are the names we can confirm and the myths we can debunk, assuming no recent supplier swaps:

Confirmed.

Websites including Dog Food Insider claim that Kirkland Signature Dog Food is actually manufactured by Diamond Pet Foods, also known as Schell and Kampeter, Inc.

That might not be enough evidence on its own, but in 2012 the Kirkland brand was part of a recall for Diamond dog foods following a salmonella outbreak at Diamond’s production plant in South Carolina. Costco and the Kirkland brand were both named in a class-action lawsuit.

There’s been no word of a break with Diamond following the incident, and the Kirkland brand remains popular with pet lovers.

Confirmed.

Even coffee snobs may be intrigued by a few of Costco’s relatively inexpensive house blends, which boast of their ties to the world’s largest coffeehouse chain.

Kirkland offers certain varieties of its house blend with the stamp, “Custom roasted by Starbucks.”

The two-and-a-half-pound Starbucks-affiliated bags include Kirkland’s Signature House Blend Medium Roast, Espresso Blend Dark Roast and Decaf House Blend Medium Roast.

Confirmed.

While Kirkland Signature’s Infant Formula was once a product of Abbott Laboratories — the makers of Similac — it seems the brand has converted to Perrigo.

A USDA report to Congress on baby formula prices and availability says Abbott Laboratories began producing infant formula for Costco under the store brand label in 2001.

However, veteran parents have noticed the yellow box of Kirkland’s Signature Infant Formula has since been replaced by a blue box bearing the name Kirkland Pro-Care Infant Formula.

Perrigo’s StoreBrandFormula.com, which catalogues the company’s retail relationships, includes Costco on its list of partners and links directly to the Kirkland Signature Pro-Care Infant Formula on Costco’s website.

Confirmed.

It’s in the name.

Kirkland openly teamed up with candy company Jelly Belly to sell its signature “gourmet” jelly beans. At Costco you can get four-pound jars of sugary goodness featuring 49 different flavors that are kosher and fat free.

Assuming an equal distribution of beans, that means you’ll be able to enjoy a full 1.3 ounces of your favorite flavor in every jar.

Confirmed.

Many buyers avoid store brand batteries for fear they’ll drain faster than the ones produced by the big name brands. You won’t know until your device drops dead at the most inconvenient time.

Thankfully, Costco’s generic batteries are made by a company that’s “Trusted Everywhere.”

Costco CEO Craig Jelinek revealed that Duracell is the manufacturer of Kirkland Signature Batteries in an interview with Atlanta station WSB-TV in 2016.

Denied.

Plenty of people will tell you with confidence that Costo’s vodka is a duplicate of Bacardi’s Grey Goose, produced in France. And the now-defunct alcohol research site Under the Label reported that both vodkas are made using water from the Gensac Springs in the Cognac region.

However, the global ambassador for Grey Goose denied the rumor in an interview with Business Insider, and Costco representatives have never commented.

Don’t be too disappointed, though. Kirkland Signature Vodka has trounced the expensive name brand in multiple blind taste tests despite being a fraction of the price.

An Alcohol and Tobacco Tax and Trade Bureau registry shows LeVecke, one of the world’s largest producers of spirits (including Island 808 and Pau Maui vodkas), applied to supply vodka under the Kirkland label, though it's unclear if that's the full story.

Confirmed.

Next time you’re hankering for some white albacore, don’t worry about sacrificing quality for cost.

In a 2003 interview with Money magazine, Costco executive vice-president Tim Rose argued that the canned tuna available on the market had declined in quality for years. So Costo struck a deal with global seafood company Bumble Bee to make a meatier product, just “like it used to be.”

The new “superior quality” solid white albacore hit shelves in 2002.

Confirmed.

Unlike the “Parmesan” you sprinkle out of a can, the name Parmigiano Reggiano can only be applied to hard cheeses made in certain regions of Italy and subject to strict standards.

Anyone trying to pass off their product as the genuine article can expect a visit from the Consorzio del Formaggio Parmigiano-Reggiano.

The back of Kirkland’s parm shows the 24-month aged cheese is “specially selected” by Formaggi Zanetti, an Italian company that exports cheeses around the world.

Just speculation.

Rumor has it that those affordable sets of cream-and-purple Kirkland Signature Moisture hair care bottles have high-end origins.

On Reddit and around the web, you’ll find a lot of speculation that L’Oréal’s Pureology division could be behind Costco’s shampoo and conditioner. However, there doesn’t seem to be much evidence.

The bottles look pretty similar, and reviewers online suggest Kirkland’s product is a fine replacement for the Pureology version. Take from that what you will.

Confirmed.

Kirkland Signature Diapers are made by Kimberly-Clark, the same manufacturer responsible for trusted nappies such as Huggies and GoodNites.

Costco finance chief Richard Galanti confirmed the connection in a 2017 interview with the Wall Street Journal. Costco had asked both Kimberly-Clark and rival corporation Procter & Gamble to produce diapers under the Kirkland brand, however only the former agreed.

Parents will notice that the only name brand diapers sold at Costco are Kimberly-Clark’s Huggies. Procter & Gamble’s Pampers are nowhere in sight.

Confirmed.

Costco partnered with New Zealand-based Reynolds of aluminum foil fame to produce its Kirkland Signature Foodservice Foil.

The proof is on the packaging, with the Reynolds logo proudly displayed on the shiny blue boxes.

The Kirkland foils come in larger sizes than the regular Reynold foils on Costco’s website, and their higher prices reflect the difference.

Looks likely.

Depending on where you live, your Costco’s Kirkland craft beers could originate from one of two places. The Takeout claims that Kirkland beers on the East Coast come from Matt Brewing in New York and that beers in the West link to Gordon Biersch.

The publication says West Coast Kirkland beer bears the name “Hopfen Und Malz Brewing Co.” on the label. The site Mashed adds that the address of Hopfen Und Malz matches that of Gordon Biersch in San Jose, California.

Meanwhile, Mashed says, beer on the East Coast bears the name Bricks and Barley Brewing Company from Stevens Point, Wisconsin. It’s unclear whether this company is related to Matt Brewing, which makes Saranac and Utica Club.

The regional divide remains unconfirmed, but an Alcohol and Tobacco Tax and Trade Bureau registry shows both Gordon Biersch and Matt Brewing have applied for labels under the Kirkland brand. Wisconsin’s Regal Brau also makes an appearance.

Confirmed.

A staple at house parties, Costco’s giant packs of disposable red cups come from a familiar place.

The packaging clearly bears the blue Chinet logo under “Kirkland Signature” and next to the bold title “The Big Red Cup.”

The American company Chinet has produced disposable tableware such as plates, bowls and cutlery for over 90 years and sells them through other big retailers like Target.

Looks likely.

After filing for bankruptcy in 2009, California’s Humboldt Creamery was sold to competitor Crystal Creamery and started selling its products nationwide through retailers like Walmart.

ABC’s KRCR News reported in 2016 that Humboldt has been manufacturing vanilla ice cream for Costco under its Kirkland Signature house brand.

However, Humboldt Creamery’s vanilla ice cream has also appeared under its own name at Costco, and both products have disappeared from store shelves at times — so the supplier situation may not have settled yet.

Confirmed.

While other theories regarding Kirkland Signature’s alcohol selection have either been debunked or unconfirmed, Costco’s scotch is definitely a product of independent bottler Alexander Murray.

In a 2016 interview with Market Watch Magazine, Alexander Murray president and CEO Stephen Lipp confirmed that the company supplies its scotch to Costco. The magazine says the independent bottler has been behind the Kirkland Signature house brand since 2007.

If you take a closer look at the Kirkland Signature Blended House Whiskey or Single Malt Scotch, you’ll also notice the Alexander Murray & Co. Ltd. label on the bottles.

Confirmed.

Water does taste different depending on the brand, though Kirkland Signature water will probably taste identical to other private labels out there.

Family-owned Niagara Bottling, which calls itself "the industry leading private label bottled water supplier in the Western United States," is behind Kirkland Signature Purified Water, according to the label on the bottle.

Niagara Bottling also sells water from spring to sparkling under its own brands Niagara, H2O+ and V-ssentials.

Looks likely.

Yogurt giant Ehrmann, of dairy delights such as Yoginos and LACTO Zero, could also be the brand behind Kirkland Signature Greek Yogurt.

In his 2017 book Disciplined Growth Strategies, American businessman Peter Cohan says that Ehrmann Commonwealth Dairy supplied Greek yogurt under private labels to a number of retailers, including Costco.

Ehrmann also produces Greek yogurt under the Green Mountain Creamery and Liebe brands.

Confirmed.

Warren Oil Company is speculated to be the manufacturer behind Walmart’s Super Tech and Amazon’s AmazonBasics motor oils, but we can confirm it supplies the Kirkland variety.

Kirkland Signature Full Synthetic SAE 5W-30 Motor Oil displays its maker in fine print on the back of the jug: “Manufactured by Warren Distribution, Inc.”

Warren, which claims to be one of North America’s largest independent lubricant manufacturers, markets its products around the world under several brands, such as MAG 1, and under private labels as well.

It's complicated.

While other grocery stores might offer more varieties of wine, Costco doubles down on quality and price. Its Kirkland Signature wines are the product of cut-rate contracts with established wine makers and importers.

An Alcohol and Tobacco Tax and Trade Bureau registry links Kirkland Signature’s California wines to E&J Gallo Winery and its Italian wines to Ethica Wines. The bureau regulates and collects taxes on alcohol, tobacco and firearm trading within the U.S.

E&J Gallo Winery produces its own vino but also distributes products from other California wineries to countries around the world. (Think Carnivor or Naked Grape.) It's unclear whether it has a hand in actually making Kirkland wine or is just a middleman. Meanwhile, Ethica Wines specializes in importing Italian wines like Borgogno and Bellavista.

More digging within the tax and trade bureau’s registry reveals Kirkland French reds are connected to Misa Imports, while listings for port, sherry, cooking and dessert wines are linked to Kobrand’s Joto Sake. One Kirkland white wine was linked to famous director Francis Ford Coppola’s winery, and a California red was affiliated with Grove Street Winery.

Confirmed.

Turns out those addictive packs of chocolate-covered nuts you grab at Costco to snack on your drive home come from the “manufacturers of the finest chocolates since 1939.”

A 2013 issue of The Costco Connection magazine reported that Costco gets its Kirkland Signature chocolate through Blommer Chocolate Company, the largest cocoa processor and chocolate ingredient supplier in North America.

Together, Costco and Blommer developed a sustainability program for cocoa sourcing in West Africa’s Ivory Coast, where most of the store’s chocolate comes from. According to The Costco Connection, the farming agreement ensures a high quality and traceable product while providing fair wages, education and other services to local communities.

Confirmed.

If you get your hearing tested at Costco — which is completely free of charge — you might be advised to pick up a set of these.

The sleek new Kirkland Signature (KS9) 9.0 Digital Hearing Instruments come in five different colors and use special wireless tech powered by Sonova, according to a hearing health and audiology magazine.

The Hearing Review reported in 2019 that Sonova confirmed it was contracted to supply its products to Costco under its flagship brand. Sure enough, Sonova is listed as the manufacturer at the end of the owner’s manual.

Just speculation.

Kirkland Signature’s bourbon may have a new supplier following a supposed switch.

An Alcohol and Tobacco Tax and Trade Bureau registry points to the famous Jim Beam as the producer behind Kirkland Signature’s Kentucky bourbon. At least, that was the case a decade ago.

By some reports, the Kirkland bourbon “distilled and bottled by the Commonwealth of Kentucky” has vanished and been replaced by “Tennessee Straight Bourbon Whiskey” on store shelves.

According to Punch — an online wine, spirits and beer magazine — distillery George Dickel is the best bet for the current supplier of the new whiskey.

Confirmed.

You don’t need to look hard to source this one. Kirkland Signature Aged Balsamic Vinegar of Modena boasts of its 100-year-old manufacturer on the bottle.

Costco partnered with Modena-based company Acetum all the way back in 1999 to produce its balsamic vinegar, according to The Costco Connection.

Like the name “Parmigiano Reggiano” for cheese, “Balsamic Vinegar of Modena” is a protected title that can only be applied to products that fit certain geographical and processing standards.

Looks likely.

Although neither company has confirmed the connection, German company Henkel is speculated to be the brand behind Kirkland Signature detergent.

In 2008, The Salt Lake Tribune reported that Huish, “the largest manufacturer of private-label laundry detergents and fabric softeners in North America,” would merge with Unilever’s laundry detergent division. Huish, it said, also made products for Costco.

The merger formed Sun Products, which is now a leading laundry care brand known for products such as Snuggle, All and Sun. Then in 2016, Henkel acquired Sun Products. Henkel itself produces popular laundry detergent brands, like Persil.

Following this long and confusing history, it seems likely that Kirkland Signature laundry detergents are now produced by Henkel. Reviewers certainly think so.

Looks likely.

This one’s all about the numbers. According to Mashed, all tequilas have an identifying number, or NOM, that can be used to track where they came from.

Thrillist once reported that Kirkland Signature Añejo tequila came from the same source as Ed Hardy Tequila, but that seems to have changed.

Citing the database of Tequila Matchmaker, Mashed says all three Kirkland tequilas now point to La Madrileña, a Mexian wine and liquor company.