Features:_x000D__x000D_The bearing is made of high carbon chrome ball bearing steel which is of good hardness and strength. _x000D_The roller way type of the bearing is spherical raceway. _x000D_The inner diameter is 12mm,the outer diameter is 39.3mm and the thickness is 20mm. _x000D_Fine polished surface provides great smoothness. _x000D_Well craftsmanship provides durability and long service life. _x000D__x000D_Specification:_x000D_Item Type: Track Guide Roller Bearing_x000D_Model:LFR5201-14 KDD/LFR5201-14 NPP(Optional)_x000D_Size:(Inner Diameter x Outer Diameter x Thickness)_x000D_12 x 39.3 x 20mm / 0.47 x 1.55 x 0.79in _x000D_Material:High Carbon Chrome Bearing Steel_x000D_Roller Way Type: Spherical Raceway_x000D__x000D_Package List:_x000D_1 x Bearing 1The roller way type of the bearing is spherical raceway. 2The bearing is made of high carbon chrome ball bearing steel which is of good hardness and strength. 3The inner diameter is 12mm,the outer diameter is 39.3mm and the thickness is 20mm. 4Fine polished surface provides great smoothness. 5Well craftsmanship provides durability and long service life.