Callaham Stratocaster Tremolo Bridge, Vintage, w/Pop-In Fender-Length Arm. 2-7/32" Screw & String Spacing. Read Description For Fit List. Complete Unit as Pictured. Made in the USA using premium vintage-correct materials. Complete tremolo unit, as pictured. 2-7/32 screw spacing, and 2-7/32 string spacing. Vintage fit, vintage feel! Features Callahams Enhanced Vintage block and Virtual Pop-In arm. Arm fits snugly, with no play. Hardened steel saddles (over 100 Rockwell B) - nickel plated - for great tone, great looks! 1018 cold-rolled steel block like the vintage originals for better sustain & harmonic content.