A sex position aid is any item that can be used to support the body during sexual activity. Some sex position aids are designed for specific activities such as spanking benches, fisting slings and doggy-style straps while others are more multi-purpose, like wedges or swings.
More About Sex Position Aid
Reasons for using sex position aids vary from simple comfort, as they can support weight and make certain sex positions easier to maintain, to BDSM play— bondage equipment such as stocks and pillories fit into this category. Sex position aids can allow partners to achieve angles of penetration they are not capable of on their own.
Sex position aids can be of particular help to people of a larger size or those with accessibility concerns, as they can take pressure off joints and better position the body for sexual access. In these cases, wedges and props can be particularly helpful as can straps that allow distribution of weight to either a fixed location or to a partner.