This bearing bushing set works extremely well with 9mm, 10mm, 11mm, & 13mm Diameter Guide Roller Ball Bearings. Whilst the bushing is threaded itself, it makes the screw more powerful less susceptible to flex. Additionally, because of the improved energy, the roller angle are less inclined to alter even yet in the function of a large crash. Also, in case nut that secures the roller precipitates, the bushing wont quickly come loose. Threaded Bearing Bushing x4 Wrench x1 Thread means roller will continue to be connected considerably longer if its attaching nut occurs in the future off. Right for rollers: items 15344, 15345, 15475.