Duplex sprocket for 12B chain, 1.chain sprocket,standard sprocket 2.idler ... sprocket 4,OEM offer Sprocket for 12B-1 roller chain, The drawing is as followed, We can ... 8MM,3/8" --> 3" 5) Type: Simplex,duplex,triplex, Taper Bore Sprocket, Various Holes Sprocket, Idler ... series.standard sprocket, idler sprocket, stainless steel sprocket,chain sprockets etcPlease contact us to get further information. ...