Features: These bearings are made of high quality steel for low noise and long service life. They are double rubber sealed to avoid contaminants entering and save lubricant. Bearings have a 17mm inner diameter, a 30mm outer diameter, and a 7mm thickness. These are great for 17mm shaft/rod projects such as mechanical equipment,electrical instruments, toys. There comes total 10 pieces miniature bearings which you may use for many different projects. Specifications: Type: 6903-2RS Material: Steel Seal: Double rubber seal Inner Diameter: 17mm/0.7in Outer Diameter: 30mm/1.2in Thickness: 7mm/0.3in Quantity: 10pcs Weight: 174g(approx.) Package Includes: 10 x Bearings 1、These bearings are made of high quality steel for low noise and long service life. 2、They are double rubber sealed to avoid contaminants entering and save lubricant. 3、Bearings have a 17mm inner diameter, a 30mm outer diameter, and a 7mm thickness. 4、These are great for 17mm shaft/rod projects such as mechanical equipment,electrical instruments, toys. 5、There comes total 10 pieces miniature bearings which you may use for many different projects.