1.Use the single (double)scale,Which is in metric or inch units 2.With a faxed scale and a sliding scale 3.Auto lock Dial caliper:CR-K131-11151.Use the single (double)scale,Which is in metric or inch units2.With a faxed scale and a sliding scale3.Auto lock 4.With Mono black.5.Made of harden stainless steel. Belows are same series diffrent models: vernier caliper mono block with auto lock