designed to reduce injuries and trauma to the upper body the mtnpro vest provides full front, side and back protection with 1 mm of hard shell sandwiched between two layers of pe foam. includes zippered front pocket, adjustable waist belt and side panels, and d-ring tether loop for attaching sled kill switch. the refillable float compressed air cylinder is the power and driving force behind our float system. when the float trigger is pulled, it activates the release of 3,000 psi (207 bar) of compressed air, inflating the airbag. always make sure your cylinder is full and connected correctly before heading out. (cylinder must be ordered separately. it isn't included with vest.)