[DURABLE CONSTRUCTION]-- Made of Metal, easy to dissipate heat, and it can provide the flexible rotation that make it durable. [PROVIDE SMOOTH MOTION]-- With spacer, axle and extra side plug to fix the bearings better, which is helpful to reduce drag on your bearings and make the motion of bearing more smoothly, helping to prevent your bearings from collapsing. [EASY TO MATCH]-- The recessed part of the spacer fits between the bearings, providing a seamless integration to the wheels, which makes it easy to support the wheels and bearings, and they are easy to match the skating male and female axles. [COMPATIBILITY & SIZE]-- Axle diameter 6mm, frame spacer inner diameter 6mm, wheel spacer inner diameter 8mm, suitable for most roller skates model using 6mm axles. Please check the specifications in the second product image to ensure it match your specifications. It is very important to measure your wheel bearing dimension to ensure a proper fit. Style:A / B Colour:silver Material:Metal Package Contents: 10 * Axle 2 * wrenches 16 * side plugs 8 * three-section aluminum casing 10 * Screws / 10 * Axle 2 * wrenches 8 * three-section aluminum casing 10 * Screws Only the above package content, other products are not included. 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 +/- 1-3cm.