The ResoMax4mm bridge is made from our ResoMax alloy. ResoMax is a lightweight, high strength, and full of harmonics that will leave your guitar dripping with tone. All ResoMax bridges feature our patented magnetic lockto the steel posts that come with it. 4mm posts are used in a lot of American and European-built guitars, including Gibson, Godin, and Duesenberg. The NV1 bridge is loaded with ResoMax alloy saddles to retain the 2KHz bite of metal saddles. Triple-plated finish for durability and good looks. 4mm post.