The optional backpack strap is compatible with most Protec cases and bags. Features a weather resistant 1680 ballistic nylon exterior, thick padding with a breathable mesh backside, sternum support, and is designed to compactly fold into a storage pocket. Compatible with most Protec cases and bags Thick padding Weather resistant 1680 ballistic nylon exterior Breathable mesh backside Durable and lightweight hardware Folds for easy storage