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: A harness, which attaches the system to the diver, and may support other accessories.