SMOOTH : With polished smooth , it works well with high efficiency and makes little noise. WORKS UNDER -20-200 ℃: High temperature resistance, to work in a temperature range of -20-200 ℃ or so. Can be used in many different environments. : Using premium bearing steel material that is solid enough for long-term use has a long service life. APPLICATION: Suitable for industrial machinery, cars, ships, home appliances, healthcare system, etc. DOUBLE SHIELDED DESIGN: 2 rubber seals protect it from the ingress of water and dust or other objects. Model: 6001- Inner diameter: about 12 mm/0.47 inches Outer diameter: about 28 mm/1.10 inch Thickness: about 8 mm/0.31 inch Operating temperature: -20-200℃ size:12x28x8mm Material:Bearing steel colour:Silver Package Contents: 20 x ball bearings Only the above package content, other products are not included. Note: Light reflection 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 +/- 1-3cm.