Like new CamelBak Raceback hydration shirt. It's a base layer shirt with an integrated hydration pouch! I used it once, but didn't find it to my liking. Size Men's medium.

Vest design offers maximum mobility and comfort under any jersey. Pouch holds a CamelBak 72 oz. reservoir firmly on your back
Chafe-Free flat seam stitching eliminates abrasion along seams. Full zip makes it a breeze to get on.
Air Mesh insulated back panel insert keeps your back cool and comfortable while insulating the water in your reservoir
Insulated tube cover keeps water in the tube cooler and more desirable to drink.
Quickwick fabric keeps you dry and comfortable.