Original Warmink sawtooth or gravity clockwork, in overhauled condition. Our clock repair man has found a way to make these small clockworks reliable. He used on major spots new bushings and on the rail gear he used a bearing bushing. That has come out very well. This clockwork has test run for many hours and has not given any trouble since. It is the small version of the available clockworks approx 2″ or 5 cm. If you buy a replacement sawtooth clockwork from us, we offer a 50 us dollar refund plus shipping on the purchase price when you send us your old clockwork.