Invented by Greg Flanagan in 1979 for North Florida cave divers. Greg realized that a back-mounted buoyancy system gives a diver natural balance in the water, due to the diver's center of gravity (tanks) being surrounded by the center of buoyancy (BC/ wings). In addition, the diver gains a clean chest area with room for gear attachment points on the harness. Bill Hogarth Main went on to popularize the backplate and harness and dive purists who follow the DIR philosophy have come to embrace what is known today as the "Hogarthian Rig". Dive Rite began manufacturing backplates for the public in 1984 and pioneered 11-inch on center bolt spacing creating an industry standard that is still followed today. Sturdy, yet lightweight, the aluminum backplate is ideal for twin backmounted steel tanks since additional weight from the plate is not necessary. Eleven-inch on center holes accommodate standard double tank bolt kits and holes along the perimeter of the plate allow for mounting lights, pony bottles, lift bags and other accessories. One-inch and two-inch slots along the bottom permit diver's choice of crotch straps. Two 3/8-inch slots along the bottom are designed to fit screws for attaching lift bag sleeves, sidemount butt plates or other accessories. Two-inch slots along the center allow single-tank divers to use cam straps without a single tank adaptor. All edges are beveled to eliminate sharp edges and prevent abrasion to harness webbing. Anodized black aluminum. Made in the U.S.A.