Starrett blade micrometers are suitable for accurately measuring depths & diameters of narrow grooves, circular form tools, keyways, slots, recesses and depths between fins. They feature a balanced frame & thimble and advanced sleeve design with distinct figures & staggered lines for better readability with easy handling and speeder for quick adjustments on all size workpieces. They come with a ribbed, rigid steel frame for impact strength and selected models have hard & stable 1 piece friction thimble for allowing uniform contact pressure & one hand operation. Choose from a wide range of these micrometers, available in mechanical & digital display options.