Zealous Bearings for Skateboards and Longboards (Steel) BUILT IN SPACERS AND SPEED RINGS - .4045 built in spacers and .5mm built in speed rings mean no more small parts to lose when changing wheels/bearings. LOW FRICTION = FAST - The coefficient of friction is the lowest in the field of Tribology at 0.003% creating a near frictionless surface. GREEN (Steel) and WHITE (Ceramic) - Color coordinated rubber seals to keep dirt and debris on the outside of the bearing increasing the longevity. PREMIUM LUBRICANT - Lubed with a Custom Nanoceramic Grease that "self heals". Grease enters imperfections in the metal and smooths them out, making for a faster bearing. 8MM AXLES - Precision 8mm axle holes fit all skateboard trucks for a super fast and smooth ride. Comes with 8 bearings (enough for 4 wheels).