1It is made of bearing steel material which makes it durable and resistant to deformity under heavy loads. 2Rolling bearings use rolling elements to maintain the separation between moving parts to reduce rotational friction 3Exquisite mechanical design makes little noise when rotating. 4The products are mainly used in high-speed motors, precision motors and other equipment with high precision requirements. 5Fine workmanship, smooth surface, excellent mechanical properties. Feature: It is made of bearing steel material which makes it durable and resistant to deformity under heavy loads. Rolling bearings use rolling elements to maintain the separation between moving parts to reduce rotational friction Exquisite mechanical design makes little noise when rotating. The products are mainly used in high-speed motors, precision motors, 3D print machine and other equipment with high precision requirements. Fine workmanship, smooth surface, excellent mechanical properties. Specification: Material: Bearing steel Model:U604ZZ Product dimension: inner diameter: 4mm, Outside diameter: 13mm, width: 4mm Package list: 10 * roller bearing Note: The actual product color may deviate from the photo due to light. There may be a slight deviation in the measurement of product.