11/13T Mountain Bicycle Rear Derailleur Guide Wheel Ceramic Bearing Tension Pulle Features: 1.Lightweight aluminum alloy metal bearings for longer service life and more efficient and stable transmission. 2.Strong compatibility to meet different sizes, new design of the spring, riding without chain, suitable for 8, 9, 10, 11 speed rear derailleur, mounting shaft O.D. is compatible with 4, 5, 6mm. 3.Suitable for tension & chain guide, some guide wheels can only be used as tension wheels but not for chain guide wheels, TOOPRE's guide wheels are compatible with both chain guide and tension wheels by adopting a clamping spring fixing structure. 4.The zirconia ceramic ball, with self-lubricating and maintenance-free characteristics, makes the rear derailleur turn smoothly, and at the same time, the transmission efficiency is higher, which saves riding power! With the new type of spring fixing structure, it solves the problem of chain jamming and guarantees the rear derailleur to change speed smoothly and run stably. 5.Multi-color laser marking selection of mainstream colors, giving accessories different colors Specification: Material: metal bearing + ceramic ball Color(Optional): red, black, blue, gold, colorful Model: 11T, 13T Weight:19g(11T),20g(13T) Suitable for: 4, 5, 6mm screw holes, 8, 9, 10, 11-speed variable speed systems Package Include(Optional): 1*Ceramic Perrin Guide Wheel(11T) or 1*Ceramic Perrin Guide Wheel(13T) Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.