Unfortunately Floyd Rose gave out licenses to anyone willing to pay his price. This means there are 5 or 6 sizes of these little blocks. Buy a cheap caliper and figure out which one you need, or make due. A competitor of Allparts who shall remain unnamed has 3 sizes of blocks in sets of 6 only. Allparts sells these by the 50 pack. Nice item to have on hand! They may fit sloppy in some bridges, or not at all in some of the licensed Korean ones. I wish I had Floyd Rose's licensing revenues. Better yet I wish I had a nickel for every time someone complained about their Floyd Licensed trem and or the parts for it, and a dime for every one that wore out, or lost parts, including originals. These can be made to work in most Floyd Rose tremolos.These blocks just get lost. I guess pressing, stamping, or clipping them onto the screws was too much trouble. ABR 1s were just as bad from pre1952 to about 1963 for loosing saddles. Then they added the wire clip.