ThermoBak AB is a low-profile solution that offers the versatility to be worn as a standard hydration pack or attached to the back of the IOTV/MTV with our Direct Armor Attachment System â„¢ (D.A.A.S.â„¢). Updated with durable 500D Double-rip Cordura Fabric and the new 3L, 100oz Mil Spec Crux Reservoir, the ThermoBak AB maintains it's minimalist footprint while offering 25% more water per sip.