This TKI Billet offset 4 wheel axle kit will allow 180mm or 200mm Ski-doo wheels to be changed to 8" or 9". This reduces rotating friction by allowing the track to bend less as it rotates around the rear skid wheel. These are machined for 25mm bearings and wheels must be ordered separately. These are a great addition to the 2015 Ski-doo's Freeride 137 and B/C for riders who run trail more than powder and gives a little extra security to make it home as the 2 wheel axles have ruined many a trip. NEW for 2018 these coem with inserts for the REC GEN4 also. Order wheels separately.