Bones only puts out the best. And with minds like Kevin Reimer behind the product, you know it was extensively tested. The hard insert reduces hanger play, which basically makes your trucks perform better in every way possible. To gauge for consistent stability, anticipate to ride a softer durometer than your previous bushings. They are sized to fit all longboard trucks that matter.
Here's what it says on the package, and they don't appear to be lying either:
-Patented bonded-insert technology
-More precise steering
-No break-in period
-The BEST bushings, period.