This feeler gauge set from Beta Tools includes 20 precision steel blades from 0.05mm to 1.00mm thick (0.002" to 0.040") in 0.05mm increments. The blades are contained safely inside the handle when not in use, and swivel out easily when needed. This tool is a must for every automotive toolbox, but critical when working on solid-lifter engines (like Formula Ford 1600 and Pinto-engined FC / S2).
The 100mm (3.95") blades are long enough to reach for most jobs but not so long they risk kinking in normal use. Blades measure 10mm (0.4") at the widest point and taper down to a 3mm (0.1") radius at the end.