The core components of this system are:[1][2] 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.

[1][2] 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.

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.

Once adjusted, some flexibility is still allowed by positioning the buckle, which can change the effective length of the waist strap depending on where it is secured.

Omitting the buoyancy bladder reduces the setup to a plain backpack harness if the breathing set needs to be used on land.

The backplate is usually made from a single piece of stainless steel or anodised aluminium, bent along four lines to form a shallow channel running vertically down the center.

[1][2] A variation on this design uses another two parallel bends to form a shallow trough down the back of the central channel, which stabilises a single cylinder strapped to the centreline, with two pairs of slots for a pair of cambands.. Steel backplates are commonly used when the buoyancy of the diver's other equipment (primarily cylinders and exposure protection) would need a weightbelt, as the negative buoyancy of the steel plate can replace some of this weight.

Wings are usually oval (annular, doughnut or toroidal) or U-shaped (horseshoe), and are designed to wrap slightly around the diving cylinder(s) when inflated.

Arguments for and against are: Some manufacturers, such as OMS and Dive Rite make both and let the purchaser choose which style they prefer.

Detractors of this arrangement point out that if the extra bladder is inadvertently inflated, the diver may not realise that this has occurred, and it may result in an uncontrolled buoyant ascent, with a risk of fatal injury.

Single skin wings may use a bellows fold gusset to increase inflatable volume while retaining a relatively compact outline.

The STA is a small metal structure that bolts onto the backplate on the outside of the wings, contains two camstraps, and accommodates the cylinder.

The buoyancy of a backplate is often significantly negative, especially when the plate is made from stainless steel, and so can replace some of the weight that would otherwise be worn on a weightbelt.

Ancillary features that would often be present in jacket BCDs, such as pockets or weight integration, are not found in the core system of a backplate and wing, but can be added as additional components if desired.

Florida cave diver Greg Flanagan has been credited with inventing a backplate in 1979 to prevent twin cylinders from shifting during a dive,[5] but it is possible that similar systems were in use earlier.

The traditional backplate and wing harness has the benefit of reduced points of failure(due to it usually being a single piece of webbing with the front locking buckle the only break), ability to modify to personal requirements and stronger, safer, points for carrying equipment, and if needed to be attached to in a rescue scenario.

Being able to use the same harness to adapt as needed through one's diving career is an added advantage (single tank, dual, rebreather etc) can make it a more economical approach also.