Comfortable,streamlinedwaytocarryaponycylinderonyourback Fits 13, 19, 30 or 40 cu. ft. pony cylinders with 4.0 - 5.4" diameters Two trim pockets, with hook and loop release tabs, hold up to 5 lbs. (2.3 kg) each Two stainless steel D-rings for critical accessories Rolled neoprene neck collar for maximum comfort Knife mounting grommets are ideal for Rook Knife (p/n KN500) Two-way adjustable sternum strap Includes two short length tank cam straps (p/n BP550) Extra large thumb loops for cinching down shoulder straps