The Tiny-Clutch 1930 Indexing Spring Clutch is based off of our SP75D Wrap Spring Clutch. This clutch features a 19 tooth, 25 pitch Sprocket, a 1 lug (Single Revolution) collar & an over-tavel stop. It has a 3/8" | 9.5mm bore, mounts with a cross hole, & replaces R. Funk Part # A18676. If you have special needs for your application please Let Us Know.