Each double-locking kit includes the locking bridge, whammy bar, 4 tremolo springs & claw, 2 pivot posts & bushings, locking nut and 2 Allen wrenches for adjustments. Single-locking kits contain everything but the bridge is non-locking. Only the nut locks the strings. The Original design Floyd Rose kit has everything PLUS a String Tree. It contains 3 springs instead of 4.