1、Aluminum Material: The main body is made of high quality aluminum material with high strength and wear resistance, having good performance for long service life. 2、Fine Workmanship: Manufactured with CNC machining for accurate size, has a close fitting, simple for install and removal, saving your time and energy. 3、Special Structure: Built in smooth bearing which is more energy saving, using the 2 front and 4 rear bearings layout, low maintenance cost, riding more energy saving. 4、Working Principle: The integrated 4 pawl ensures effective fitting by increasing the number of slots on each pawl, providing a satisfying using experience. 5、High Efficiency: Up to 54 teeth of the ratchet teeth, 4 pawl 12 teeth bite at the same time, pawl can bite the ratchet teeth when the Angle is very small, reduce the loss of force. Item Type: Bike Hub Material: Aluminum Alloy Color: As Picture Shown Gross Weight: Approx.658g/23.2oz Front Bike Hub: Approx.100x9mm/3.9x0.35in Rear Bike Hub: Approx.135x10mm/5.3x0.4in Number Of Holes: Front 28 Holes, Rear 28 Holes, Straight Pull Bearing: Front: 2 Bearings, Rear: 4 Bearings Application Speed: for Mountain Bike, Road Bike 1 x Front Hub 1 x Rear Hub 2 x Quick Release Skewers 1 x Washer