R188 CERAMIC BALL BEARING engineered with proprietary specific internal race tolerances for high speed reliability. Sealed on both sides as shown. The width of this bearing is 3/16". Overall dimensions of this bearing is 1/4" inner diameter, 1/2" outer diameter and 3/16" width. This is engineered as a very smooth and fast fidget spinner bearing but has many applications. Open design with stainless races and cage, 10 Ceramic Nitride Pro Series balls, with no seals for longest and fastest spin.