A sizing caliper (1) for facilitating the selection of a femoral component of a knee prosthesis to be attached to a resected distal end of a femur, the femur having one or more posterior femoral condyles, the caliper having a longitudinal axis L and comprising a caliper body (2) configured for engaging the resected distal end of the femur a stylus tower (4) a stylus (3) coupled to the stylus tower and having a tip: and two drill guide bodies (6b), each drill guide body provided with a drill guide hole (62a, 62b).
