Gotoh 510TS Series Tremolos are machined with Chrome Molybdeumn Steel knife edges to withstand years of abuse and trouble free use. Comes stock with a vintage steel block with more mass and better tone. These are top of the line Gotoh tremolo units. Tremolo-unit includes the following accessories: Arm, Spring, Spring-holder, Wrench, Stud-bolt, Screw etc… Hardware included.