It has a built-in pouch for hydration systems in the back. It's designed to hold Blackhawk's "Hydrastorm" line...but I have seen fellow SAR members with a Camelback in theirs. In my opinion, it will fit any bladder on the market. The Omega EOD (the one I have pictured) is a great vest, if you want some more pictures of it, just drop me a line. Here's a link to the full specifications on the Blackhawk website: Blackhawk Omega EOD Assault Vest Hope that helps!

John McIntire