IMR MJ rear sprocket for IMR Copa 155 until 2019 MJ Corse MJ.310 €23.30 High quality duraluminium (ergal) rear sprocket for IMR Copa 155 until 2019, with chain pitches 415 and 420 and with number of teeth from 30 to 46. Select the chain pitch and number of teeth you need by clicking below. Add to cart