Ball Bearing: 20 pcs Green ; of carbon steel, durability and resistance to deformity under heavy loads.Inner Bore Diameter 8 mm; Outer Diameter 22 mm; Thickness 7 mm.Steel cage evenly spaces balls for reduced friction, vibration, and noise, and is shields on both sides to protect against contaminants and retain lubrication. Great for skateboards, inline skates, roller skates, scooters, and other skating applications, also available for 3D printer wheel bearings, CNC, etc. Material: metalPackage Contents:20 * Ball BearingOnly the above package content, other products are not included.Note: Light shooting and different displamay cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Color: green Size: inner diameter 8mm, outer diameter 22mm, width 7mm Delivery Quantity: 20 Pieces