A backplate and wing is an alternative configuration of scuba harness with a buoyancy compensation bladder known as a "wing" mounted behind the diver, sandwiched between the backplate and the cylinder or cylinders. Unlike stabilizer jackets, the backplate and wing is a modular system, in that it consists of separable components. This arrangement became popular with cave divers making long or deep dives, who needed to carry several extra cylinders, as it clears the front and sides of the diver for other equipment to be attached in the region where it is easily accessible. This additional equipment is usually suspended from the harness or carried in pockets on the exposure suit. Sidemount is a scuba diving equipment configuration which has basic scuba sets, each comprising a single cylinder with a dedicated regulator and pressure gauge, mounted alongside the diver, clipped to the harness below the shoulders and along the hips, instead of on the back of the diver. It originated as a configuration for advanced cave diving, as it facilitates penetration of tight sections of cave as, sets can be easily removed and remounted when necessary. The configuration allows easy access to cylinder valves, and provides easy and reliable gas redundancy. These benefits for operating in confined spaces were also recognized by divers who made wreck diving penetrations. Sidemount diving has grown in popularity within the technical diving community for general decompression diving, and has become a popular specialty for recreational diving.