This bearing bushing set may be used with 9mm, 10mm, 11mm, & 13mm Diameter Guide Roller Ball Bearings. As the bushing is threaded itself, it creates the screw stronger and less more likely to fold. Additionally, thanks to the improved power, the roller angle normally less likely to change even yet in the function of a large crash. Also, if the nut that secures the roller comes down, the bushing won't quickly come loose. Threaded Bearing Bushing x4 Wrench x1 Thread means roller will stay attached much longer if its attaching nut happens in the future off. Suitable for rollers: Things 15344, 15345, 15475.