4531 Elite Hybrid Sport Vest: Front zipper w/mesh ventilation panels and scoop neck Comfortable, quilted nylon outer with HyperKewlTM fabric inner, water-repellant nylon liner, and black cotton-poly elastic trim Hybrid cooling solution for ultimate relief: Evaporative Cooling HyperKewlTM fabric Orovides 5-10 hours of cooling relief per soaking Phase Change Cooling Inserts maintain a comfortable 58 degrees F (14 degrees C) for up to 3 hours Include one (1) set of Cool PaxTM Phase Change Cooling Military Vest Inserts (7065 w/velcro) TechKewl Elite Hybrid Sport Phase Change Cooling Vest