464P Micrometer Heads 0-1/4" 460A Micrometer Heads 0-1/4"/0-6.5MM 460B Micrometer Heads 0-1/2"/0-13MM These are plain micrometer heads with no lock nut or ratchet. 460B 460A 464P Micrometer Heads 464P, 460A, 460MA, 460B and 460MB Micrometer Heads Cat. No. EDP Range Graduation 464P 56657 0-1/4" .001" 460A 64444 0-1/4" .001" 460MA 64445 0-6.5mm 0.01mm 460B 64446 0-1/2" .001" 460MB 64447 0-13mm 0.01mm 2" (50.8) .138" (3.51) .2362" .2358" (5.999) (5.989) 15/64" (6) 5/8" (16) 25/64" (10) 460B (0-1/2") and 460MB (0-13mm) dimensions 1-17/32" 13/16" 5/16" .4370" (11.100) .4365" (11.088) .200" (5.08) 1/2" 464P (0-1/4") dimensions 1-1/2" (38) 15/64" (6) 3/8" (9.5) 25/64" (10) .138" (3.51) .2362" .2358" (5.999) (5.989) 460A (0-1/4") and 460MA (0-6.5mm) dimensions 66 M icrometers