The 4R206 TF Test Fitness Foot Adapter in combination with a suitable socket adapter (e.g. 4R77 or 4R51) joins the 1E90 Sprinter prosthetic fitness foot to a prosthetic sport knee joint (e.g. 3S80). It is intended exclusively for trial fitting and enables selection of a suitable 1E90 Sprinter model. The foot is inserted into the adapter and can be adjusted vertically. A clamping mechanism allows the adapter to be secured and released at various heights, thereby helping to establish the suitable height and length of the foot and subsequently shorten it accordingly. The horizontal offset of the socket adapter permits anterior or posterior placement of the foot if required. Three different positions are possible.