Review on Bones Bearing Spacers - 4 Pack for Enhanced Performance by Mario Madden

i liked them, not much to say about that; Machining was good, no burrs. They are used in combination with shims to get the best speed out of your truck mounted wheel or even if you don't use skateboard bearings when you come out between the bearings you can compress the bearings and make them perfectly straight eliminating the wobble of the Bearings will be minimized and your bearings ruined, and if you have quality bearing or clean and maintain your bearings, it's worth it; Unless you're pumping a pair into each wheel, I suggest you do if you want your bearings to spin longer and last longer. This allows you to tighten the lug nuts more without braking the bearings. This means your wheels don't rattle on the truck and have less play (damaging movement for bearings and hearing).