For Single Bearing Wheels on Dual Bearing TrucksWant to ride wheels like Oak Wheels or Blackriver Wheels (with only one bearing) on Ytrucks or Blackriver Trucks Dual Bearing Edition? FBS Spacers make it possible! Each spacer is 1.0 mm wide and has a diameter of 3.0 mm. Why you need them:Dual Bearing Trucks have a longer axle. Without spacers, single bearing wheels sit loosely and don’t roll properly. The solution:FBS Spacers replace the second bearing and ensure a secure fit and optimal performance of your wheels. Compatible with: Blackriver Trucks Dual Bearing Edition Dynamic Trucks Dual Bearing Edition Ytrucks Single Bearing Wheels (e.g. Oak, Blackriver, FlatFace and many more)