Made of high resistance stainless steel. Indicated for patients with a maximum weight of 125 kg. Ring adapter with pyramidal receiver with cord M36 x 1.5. It is used in combination with knee units 3I15, 3A40, 3I20, and any adapter to socket (such as spare part 4I41, 4I111) or rotating square (4I77 or 4A77), for the manufacture of modular leg prostheses.