Amana Tool uses only the finest industrial quality precision ball bearings available. Bearings are double steel-shielded for extra rigidity and to inhibit dust. A special high-performance, high-temperature grease is used for maximum life., #47775, diameter (D) 3/16, application miniature router bits, B .094 (3/32), D 3/32, 47775 Miniature ball bearing guide 3/16 overall DIA x 3/32 inner DIA x 3/32 height