ITEM NAME:LMF20UU 20mm Inner Dia 4 Bolt Flange CNC Router Linear Motion Bearing P9N6 LMF20UU 20mm Inner Dia 4 Bolt Flange CNC Router Linear Motion Bearing P9N6 Package Content : 1 x Flange Linear Bearing Color : Silver Tone Material : Carbon Steel, Rubber Net Weight : 171g The universal Ball Bearings is great for you to replace the damaged Ball Bearings in your devices to improve them efficiency and save energy. Product Name : Flange Linear Bearing Model : LMF20UU Inner Diameter : 20mm / 0.8" Outer Diameter(Shaft Dia) : 32mm / 1.3" Overall Size : 42 x 54mm / 1.7" x 2.1"(L*D) Mounted Bolt Hole Dia : 4mm/0.16" Note:Light shooting and different displays may cause the color of the item in the picture a little different from the real thing.The measurement allowed error is +/-1-3 cm..Model : LMF20UU. Mounted Bolt Hole Dia : 4mm/0.16".