Shimano slx hub rear m675slx freehubs are designed specifically for mountain biking featuring a micro ratchet freehub mechanism for quick engagement these hubs are durable and reliable performers features durable construction for a longer maintenance cycle angular contact cup and cone bearing with grease sleeve ensures smooth running even in muddy conditions excellent stiffness to weight ratiofreehub body material steel axle type qraxle length 146mmover locknut 135mmspoke holes 32hspoke