Fowler-Wyler Circular Spirit Level 52-422-073-0 Features: Circular Spirit Levels are used for leveling machines and other types of apparatus Mounting diameter of No. 52-422-074 is .984" (25mm). The screw hole diameter on this model is .098" (2.5mm) Mounting diameter on No. 52-422-072 is 1.968" (50mm). The screw hole diameter is .135" (3.5mm) Other styles, sizes and sensitivities are available upon request