The Gotoh® 510 Tune-o-matic Bridge is designed for absolute stability with locking stability added for every facet of the bridges adjustment features. Allen screws lock the individually adjustable saddles in place using downward pressure through the top of each saddle while the forward and rearward angle is controlled by two allen screws on either side of the chassis at each stud location. The height adjustment studs are allen key adjustable (this bridge uses no traditional thumbscrews) and the overall bridge intonation angle is set using similar type allen screws. The result is better sustain, rock-solid intonation and improved string energy transfer. The saddles have helpful starter grooves to guide your notching files. Made of zinc. Intonation screws are phillips head. Includes three allen wrenches for each locking mechanism.