Fowler High Precision Fowler's setting masters are quick, easy and extremely accurate. Each comes with a certificate of calibration and a wood case. Save time and money by calibrating your own measuring tools. Depth Micrometer Checker: Ideal for quick, easy calibration and zero setting of depth micrometers. Range 06" Graduation: 1" Accuracy: ±.000120" Reference block: 1" ±.000020"