This is a blind hemmer - to show the difference. Left is short shank side clamp, right is top clamp White. For the White machines, you actually remove the top clamp adaptor and mount the unit directly to the round presser foot bar. White also has a bit more distance between the presser foot bar and the needle bar, so if you do manage to get one to mount on a different machine, make sure the needle is not going to hit the foot before you start sewing.
