Prosthetic socks area work over the residual limb. They come in various thicknesses and materials and provide cushioning, reduce and absorb friction, protect the skin, absorb perspiration and compensate for any shrinkage and/or swelling of the residual limb. A residual limb will change size and shape over time. Different thicknesses of socks (ply) are used to compensate for any increase or decrease in size of the residual limb. Your prosthetist will show you how to put on the sock, when to put it on and how to use the most efficient one for your needed fit.