This bearing bushing set can be used with 9mm, 10mm, 11mm, & 13mm Diameter Guide Roller Ball Bearings. Since the bushing is threaded it self, it generates the screw more powerful much less likely to fold. Additionally, as a result of the improved power, the roller angle normally less likely to want to change in the big event of a large crash. Also, in the event that nut that secures the roller comes down, the bushing won't quickly come loose. Threaded Bearing Bushing x4 Wrench x1 Thread means roller will remain connected much longer if its attaching nut takes place in the future off. Compatible with rollers: products 15344, 15345, 15475.