Lightweight Off-Road Chain Roller, Polyurethane W/Nylon Sleeve, Large, 39MM, Black, These Lightweight Polyurethane Off-Road Chain Rollers Are Designed With No Bearings And Run On A Maintenance Free Nylon Bushing. Most Dirt Bikes And Atv'S Require Two Per Machine. They'Re A Great Way To Save A Lot Of Weight On Your Machine, And Much Less Expensive Than Titanium Nuts And Bolts. Available In Two Sizes: Small, 32MM, & Large, 39MM. Seven Colors Available.