A backplate and wing (often abbreviated as BP&W or BP/W) is a type of scuba harness with an attached buoyancy compensation device (BCD) which establishes neutral buoyancy underwater and positive buoyancy on the surface. Unlike most other BCDs, the backplate and wing is a modular system, in that it consists of separable components. The core components of this system are: The backplate, a plate, usually made from stainless steel, sometimes aluminium or carbon fibre composite, which is held against the diver's back by the harness, and to which the diver's primary cylinder or cylinders are attached. A harness, which attaches the system to the diver, and may support other accessories. An inflatable buoyancy bladder known as a wing, between the backplate and the cylinder(s), used for adjusting the buoyancy of the diver when in the water. A set of cambands or cylinder bands, to hold the cylinder(s) in place. Function The backplate and wing combination is a modular form of scuba harness and back mounted buoyancy compensator used by scuba divers to support the diving cylinder and buoyancy compensator bladder on the diver's back. It also provides attachment points for accessory equipment such as auxiliary scuba sets for decompression or bailout, lights, cutting tool and guideline reel. Configuration Harness The basic harness comprises two lengths of 2" (50mm) webbing: One is woven through the slots in the backplate to form closed shoulder loops and an open waist strap, with a weightbelt-type lever action buckle for securing the waist strap, The second section of webbing forms a crotch strap, running from the bottom of the backplate, between the diver's legs, and up to the waist strap, which would be passed through a loop at the front end of the crotch strap. This harness is sometimes referred to as a one-piece harness, due to the shoulder and waist straps being made from a single piece of webbing. The harness is usually fitted with stainless steel D-rings secured by stainless steel "sliders", small slotted plates which hold their position by friction. A loop of elastic cord is normally attached at the same place as the left shoulder D-ring, to secure the wing's inflator hose. This arrangement is extremely rugged, reliable and hard-wearing. This form of harness may be adjusted to fit different builds of diver by shortening the webbing used to tighten the harness, or installing a new longer section of webbing to