The GearWrench 30-blade Deluxe Feeler Gauge measures clearances from 0.0015" to 0.035”. The Deluxe Feeler Gauge also includes a 0.010” hard brass blade to use with electronic ignition systems where non-magnetic blades are required. The convenient screw adjuster holds selected blade in position. Blades are 3-5/16” long and 1/2” wide.