These drivers were originally designed for those who were racing on asphalt. These are non-extrovert drivers they are designed to drive off of the four row's of drive bumps found in between the track suspension rails. If your are purchasing for 1 snowmobile, you will need to order 2. These do not have antiratchet points. If you have a Yamaha and your driveshaft is prior to the 1.75 Procross shaft please refer to our Hex Shaft Drivers.