GORUCK makes this pair of military-grade gym bags from 1000 D ballistic or double-layered CORDURA. As far as I can tell, that means they're burly and water resistant, but will probably grow to smell like a combination of the inside of your socks and the inside of your jock strap just as much as the next gym bag. You'll look cooler as passersby recoil from the stench of leg day carrying a GORUCK though.
The 20L and 38L duffels contain one main internal compartment for clothes and gear, plus an internal pocket for easy access to keys, phones, and BCAA pills. Both bags also have two external zip pockets on each end. GORUCK tests its carriers' high stress points to over 400 pounds, which is almost as much as I bench. On a recovery day.
Bags are available in 6 to 8 different colors, including a couple of different camo patterns. They're fitted with YKK zippers and 550 cord zipper pulls. The 2" x 3" Velcro on their fronts is customizable with your choice of patch--the American flag in the photos is not included with purchases, so Canadians, buy away without fear of deportation for traitorship. Stats for the 20L GORUCK are: 20" wide x 8-1/2" high x 8-1/2" deep; 1.2 pounds. And for the 38L: 24" wide x 10-1/2" high x 10-1/2" deep; 1.4 pounds.
Muchas danke to Bless This Stuff.