This Router Bit Replacement Bearing features an outer diameter of 3/8, an inner diameter of 1/4 and a height of 1/8. Typically, bearings with a 1/4 inner diameter are used on the shanks of template or flush trim router bits with 1/4 diameter. This high quality ball bearing is well constructed and will endure many hours of use. This bearing can also be used as a standard utility bearing in whichever application that bearings are used. Highlights: - Replacement shank bearing for router bits with a 1/4 shank - Polished stainless steel construction for smooth and worry-free operation - For router bits with a 1/4 shank Item Includes: 1 Bearing From time to time, router bit bearings need to be replaced due to normal wear and tear. Because you never know when a bearing will suddenly seize or break, its always a good idea to have a few extra bearings around. Bearings with an inner diameter of 1/4 or 1/2 are often used as shank bearings for template or flush trim router bits with shank diameters of those sizes. Bearings with a 5/16 inner diameter are used as part of a router bit assembly, common in tongue & groove and rail & stile bits, which are placed on a router bit arbor that has a 5/16 diameter. Bearings with a 3/16 inner diameter are used on the end of flush trim, edge forming or rabbet router bits with an end stub that has a 3/16 diameter. Our fully-enclosed bearings are smooth and well balanced and are made to withstand heavy use.