The Starrett 449, 449M Series Micrometer Depth Gage with Non-Rotating Blade includes a .045" thick x 1/8" wide (1.2 x 3.2mm) blade that can be turned with the fingers and positioned at any angle relative to the base. In operation, the blade does not turn, but moves perpendicularly only, permitting depth measurement of narrow shoulders without the blade rolling off. This is also ideal for slots and recesses as narrow as .045" (1.2mm). Furnished with a 2-1/2" (63mm) or a 4" (100mm) base. 0-75mm Range, 0.01mm Grad, 63.5mm Base, 3 Rods, in Case.