These Bones Hardcore Bushings are a Patented Double Action bushing with a chemically bonded core insert and high rebound urethane. There is no break in period, they are highly responsive to turns, provide increased truck performance and an overall improved skating experience. They are single action bushings whereby only one side of the bushing works for you at a time. Bones Bushings are the first double action truck bushing. These bearings come in 3 hardness's: Hard Bushing: 96A, Medium Bushing: 91A and Soft Bushing: 81A. There are 2 bushings to a pack.