JEGS dial indicator stand/bridge is unlike other units that are anodized, ours is hard anodized for durability and longevity. Extends over bores of up to 4-7/16''. Can be used to check piston to deck clearance, flatness of the heads or blocks, runout and many other critical measurements. Works with most standard dial indicators and JEGS dial indicator 555-81605 (sold separately). Designed for use with the cylinder head off of the block. Made In USA