3I Series injection molded waterproof cases are constructed of ultra high-strength polypropylene copolymer resin and feature a gasketed, waterproof and airtight, submersible design (IP67) that is resistant to corrosion and impact damage. Its continuous molded-in hinge, patented "trigger release" latch system, comfortable, snap-down rubber over-molded cushion grip handle, secure stacking, and automatic ambient pressure equalization valve (MIL-STD-648C) all contribute to its military grade design.