These stitcher heads were removed from an Itoh stitcher trimmer,and came new with the machine. I believe they are Osako s50 heads but i'm not sure, though they are muller style heads and will fit Osako, Muller, Itoh. They were removed to upgrade to Honer m 50/8's many years ago. Heads have 2-1/4 inch centers, one is missing a hook guide (part #881.0037.4). Other than that, it is complete.