Norton magdyno magneto sprocket, 16T, vernier adjustment. Full vernier adjuster set for magdyno. Allows timing setting accurately within 3 degrees similar to a Manx. Best change I have ever made to my Norton singles. Original part number: C2/112; 13853 - 16 tooth magneto sprocket - vernier boss - 16T plate wheel - nut - pin (to fix vernier) - washer (shouldered)