Heavy-duty FR-treated 300 denier Trilobal rip-stop polyester with PU backing gives superior abrasion, puncture, rip and snag resistance|4 Outer large storage pockets with hook-and-loop fasteners, multi pen/marker/chalk and small ruler pocket, 11" large ruler slot pocket, and 14" zippered pack across entire back area|Dual chest straps|Safety D-ring access slot on back|Cell/radio pouch pocket|4 inner storage pockets|Mesh side vents for breathability