Instead of getting a special package for my RC car I received this package of 20 pieces. Cheaper and gave me some extras! Same bearing size; fit with no problems. Smoothness/low friction is easy to see when the front wheels spin and just keep rolling. I wrecked my gearbox and smeared the bearings in it with sticky grease. The extra bearings were really helpful as I just put the dirty ones aside to clean later, put in the extras and get on with my work.