Vktech 2Pcs 42mm Guitar Locking Nut for Floyd Rose Tremolo Bridge System This is a top mount design in which the mounting screws go through the top of the unit. Larger sized 42mm (1 5/8") locking nut which can be used with your Floyd Rose tremolo, or it can be used in other designs also Easy to install, convenient to use Material: Zinc alloy Size: Approx. 42 x 15 x 15mm (L*W*H)