Sling furniture is usually a suspended, free-swinging chair, bed, or hammock that is made of a framework connected to hanging straps or rope. When attached to poles or a frame for carrying, a sling becomes a stretcher, a simple form of litter.
Purpose-designed and constructed slings are also used for sexual activities. These may be made from nylon webbing, heavy canvas, leather, neoprene, heavy rubber, even wood or steel. In general, these sex slings are intended to give free access to the genitalia, perineum, buttocks, and perianal areas while supporting the passive (receptive) partner in a comfortable position with the hips flexed and allowing him or her to fully relax. Sex slings are hung from special frames or eyebolts in the ceiling of a room or even from doorframes, depending on the design and the weight of the occupant.
There are two fundamentally different designs for sex slings, one with two variants. The most common (illustrated) is similar to a hammock and holds the receptive partner in a supine (back down) position. A variant of the hammock style is a hanging platform of wood or metal, padded for comfort. The hanging platform differs from the hammock style in that, being rigid, the receptive partner's back is straight, rather than bowed.
Both the hammock and hanging platform designs are often equipped with loops or stirrups to hold the ankles or calves up without the requiring exertion by the receptive partner. This allows the receptive partner's hips to be flexed without exertion, improving access to the areas of interest.
Hammock-style slings vary in the number of suspension points from three (two at the hips and one at the head), to four (two at the hips and two at the shoulders), to five (two each at hips and shoulders, plus one at the head. The functional difference between these variants lies in the stability of the sling when in use: the more suspension points, the less movement. Note, however, that many users of slings prefer that they be able to move.
Hammock-style slings also vary in their construction, some being a coarser or finer mesh, others of open strap work, others single pieces of material.
Another sling design is the sit sling, which holds the receptive partner upright, rather than supine. Sit slings take most of the body's weight via large padded loops around the thighs, or some similar arrangement.
Not all uses of sex slings can be considered kinky. Individuals with muscular weakness or arthritis use them so as to enjoy sexual activity without undue strain on their weak muscles or creaking joints. Slings may be used for both vaginal and anal intercourse, fellatio, and cunnilingus.