its a robotic wheel, you can use in your robo car, or any other purpose. Its 6mm hole wheel which support any gear motor with a 6mm shaft. For locking it has screw fit system inbuilt.
Wheel dia is 7cm, thickness is 2cm and hole dia is 6mm.  This wheel can easily fit in johnson gear motor, normal gear motor etc.
Package Include - 
1x Wheel