[6mm Hole Diameter]
[8mm Orange]
The spur rack is made of 45# steel, and the surface maybe with rust on some hardened rack.
package include: 5pcs Spur Rack 1M10*10-1000mm
5pcs Spur gears 1M20T hole diameter 6/6.35/8/10mm
Note:the racks arent processed and hardened.