The ResoMax 4mm bridge is made from our ResoMax Alloy. ResoMax is lightweight, high strength and full of harmonics that will leave your guitar dripping with tone. It comes preloaded with String Saver saddles to reduce string breakage and improve tuning stability. All ResoMax bridges feature our patented magnetic lock to the steel posts that come with it. 4mm posts are used in a lot of American and European built guitars, and brands such as Gibson, Gretsch, Godin and Duesenberg.