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 and do not require trimming the rails. These are diamond drive compatible. If you have an Arctic Cat and your driveshaft is prior to the 1.75 hex shaft please refer to our Hex Shaft Drivers.