Ball bearing with the dimensions 12x18x4mm, which fits perfectly on 4mm axles. This bearing is 'shielded' on both sides to prevent dust getting into the bearings.
Ball bearing (12x18x4mm) - ABEC 3 - 2 pieces★★★★★Click a star to leave your reviewWorst experience possibleA bad experienceA moderate experienceA satisfied experienceA very positive experience