DESIGN: High-quality ball bearing designed for free running against an edge to prevent heat buildup. DIMENSIONS: This bearing has an outside diameter of 1/2" (12.7 mm), an inside diameter of 1/4" (6.35 mm), and a thickness of 3/16". APPLICATION: Designed for 1/4in shank mounting, perfect for direct fit to router shanks and arbours. DURABILITY: This bearing is grease packed for maximum efficiency and lifespan, with shielding on both sides to prevent dust penetration. MAINTENANCE: Remember not to clean with solvent or lubricate as this will dissolve the grease and cause premature bearing failure.