This is our new version of the single ring Kluson® key used on all the 50's Les Pauls®. They look amazing on any new or real Paul. Now includes correct bushings and screws. Will fit standard US 1/4 inch shafts. No modifications needed for USA made guitars. If you are switching from Grovers® to Klusons®, you will need to purchase a set of new nickel conversion bushings .