A Cleavage Top refers to a prosthesis

Prosthesis

In medicine, a prosthesis, prosthetic, or prosthetic limb is an artificial device extension that replaces a missing body part. It is part of the field of biomechatronics, the science of using mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control...

 designed to provide what is claimed by the manufacturers to be a realistic looking breast and cleavage, allowing someone with little or no breast tissue to wear low cut tops and more revealing clothing while appearing to have large breasts.

Unlike breast prostheses and enhancers that need to be completely hidden and require the use of cleavage enhancement

Cleavage enhancement

Cleavage enhancement encompasses a range of techniques used temporarily to improve the appearance of a person's breast cleavage or to create the illusion of breast cleavage on a person who has no such cleavage...

 techniques to display cleavage, cleavage tops provide a full bust that can be mostly exposed without the edges of the prosthesis showing.

Cleavage tops incorporate a pair of breast prostheses in a one-piece skin coloured garment that is designed to provide the illusion of natural cleavage. Such garments have the disadvantage of having a visible top edge at the neck, which requires the wearing of a choker

Choker

A choker is a close-fitting necklace, worn high on the neck. This type of jewellery can consist of one or more bands circling the neck. Chokers can be made of a variety of materials, including velvet, plastic, beads, metal, and leather. They are often adorned in a variety of ways, including with...

 or similar necklace to hide the top edge of the garment. The edges of the breast prostheses are often distinguishable through the thin outer cover. They are usually made from either latex

Latex

Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...

 or silicone

Silicone

Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications , cookware, and insulation....

 and most often are made to measure.

Transgender

These prosthetics are marketed to pre-hormonal transwomen and males who cross-dress

Cross-dressing

Cross-dressing is the wearing of clothing and other accoutrement commonly associated with a gender within a particular society that is seen as different than the one usually presented by the dresser...

.

Retailers

The main providers of Cleavage Tops are:

Bountiful Bosoms - http://www.bountifulbosoms.co.uk

Proactive Prosthetics - http://www.proactiveprosthetics.com