These sleeves are made out of brass (non like metal) they give you a superior clamping application compared to other types of metals, they do not damage the aluminum or coatings, running these will allow you to fit forks with 54mm outside diameter into a 56mm top clamp hole ( we do not recommend running in a bottom clamp application). This product has been tested extensively with no issues, we recommend lining the slit up with the slit in your clamp (where the pinch bolts are).They are hand cut and formed in a clamp jig to assure proper fitment. We are not responsible for damages resulting from misuse or improper installation) 2 PC(pair).