4mm wide 158mm long belt and it's a good replacement for the Gtech original. If your roller stops rotating then it's most likely that this belt has snapped. Replacing this belt is very easy. Remove cover by prying open using a flat screwdriver and slip the replacement belt on. As easy as that. Gtech do not spare many parts and insist on selling you a new complete head unit for £58 plus postage. This offers an affordable alternative.
