A sterile copy of a final humeral head prosthesis designed to be used before primary or revision implant surgery to validate the proper size of the permanent prosthesis required by the patient, to ensure its proper orientation and positioning, and to verify that the implant site has been cut to the proper dimensions. It has a cup-like ball shape and is available in types such as concentric head fixation, eccentric head fixation, or types for revision surgery. It is typically made of metal and/or polyethylene (PE). This is a single-use device.