This product is made of composite plastic. Very durable and last a long time IF YOU ONLY USE IT ON SEALED ROADS. Now if you are like me and take it off road where small rock can fly around under the shell then you are best advised to purchase one of these. The bit that tends to break is the actualy rails on either side of the gear which if a stone gets into the gear can cause break the rails which then cause the belt to come off and the chain reaction destroys the rest of the rail, with it the belt drive itself. Not really the fault of the part but if you can somehow place a cover or shield where there is no belt contact then it will last a whole lot longer. Still think this is a good buy considering what it has to deal with