Harnesses are often made of leather and used for purposes in bdsm and sex play.

A "strap" or "strap-on" is a harness worn around the waist thong-style or around the waist and legs in a two strap style. Strap-on harnesses can be worn by men double-penatrating women, women wishing to have intercourse with other women, or women wishing to anally penetrate men/women. There are so many different types. Some come in kits, dildo and all, but most are sold separately. They are generally made of leather or nylon or a combination of both. They usually have a hole through them, some include changable cockrings for the perfect dildo fit.

Chastity belts are harnesses used for the purpose of preventing men or women from engaging in sexual intercourse. Generally they include a lock, securing the harness in place, locking the penis or vagina away. Usually thong style, made of leather.

There are a wide variety of body harnesses, some made for show, some for distinct function. The most common body harness sold in leather stores are x-shaped. Generally adjustible via snap or buckle, attached to an "O" ring (at center in front and back), these harnesses are worn over the shoulders and around the waist. Not super functional other then allowing a second party the ability to drag the wearer around like a puppy... though the imagination is a powerful tool. These harnesses are primarily worn by men, though are also wearable by women. An extension to this harness makes it possible for a man to attach a cockring to the harness. There are many other variations that I won't get into here.

Harness slings are fun pieces of equipment which allow people to return to their youth and suspend themselves by contraptions made of nylon and or leather via their thighs, backs, backsides, arms, etc. Some look very much like swings, but are used for naughty sexual play. These slings give people a variety of choices for positions not ordinarily attainable in normal play. They are usually hung from wooden ceiling beams and doorframes.

In conclusion harnesses serve a variety of functions for those in the bdsm world, from lesbian sex to youthlike sexual play... have fun.