(Reuters)

You'd never guess that the place where you can buy 30 packs of toilet paper and breakfast cereal by the cubic foot would also be the place where you could get all your undergarment shopping done.

But it is.

Costco is secretly one of the best places for men to get every single undergarment they need. Socks, undershirts, belts, and even underwear — all by Costco's Kirkland Signature private label.

It's all in the high-quality manufacturers Costco sources from and the exacting standards they hold for the products that carry the Signature label.

Unfortunately, it's a bit of a mystery who exactly manufactures these products, as both retailers and manufacturers prefer to keep mum about the relationships. So you won't know exactly who is manufacturing these products, but if you can live with the uncertainty, then the rewards are plentiful — as are the steals, since the items are quite a bit cheaper than their name-brand counterparts.

Socks(Amazon.com)

My favorite winter socks, the Kirkland Signature Men's Outdoor Trail Sock, is one of the best steals in all of men's sockdom. A four-pack of the merino wool blend socks is a mere $12 — an incredibly small amount of money for wool socks of this quality.

I've bought many over the years, and exactly zero have failed me so far. They're warm, soft, and, most importantly, comfortable.

Buying a comparable pair from an established wool sock brand like Smartwool would have cost $19 for one pair. Unfortunately, the socks are so popular, this year's run is already sold out, and the resellers are offering the socks for nearly double retail. It's worth keeping an eye out next fall however, when they return in September.

Belts

Another of my favorite items from Costco is the Kirkland Signature Men's Leather Belt. Though it costs a mere $18, the belt is made with Italian full-grain leather, which is the absolute best type of leather you can buy for a belt. The belt has lasted me years and still looks just as great as it did on day one. It's the perfect size, weight, and color, and I have every confidence it will last me years and years to come.

A comparable full-grain belt might cost anywhere from $50 to $100. Another steal from the bulk giant.

Undershirts

(Amazon.com)

Guys swear by the Kirkland Signature Men's Crew Neck Tee undershirts and, from my personal experience, it's easy to see why. The shirts are luxurious and thick, bucking the trend of off-brand clothing being weaker or thinner than their counterparts. They'll last quite a long while.

It's $19 for a six-pack, which might be a bit more expensive than undershirts you'd find at Walmart or Target, but the quality is much better, and the cotton is thicker.