The Starrett S668DZ shaft alignment clamp set includes two chain clamps, two 81-141J dial indicator gauges with lug-on-center backs, two PT18724 snugs, two extension plates, and various posts to perform radial and angular alignment of motors, pumps, and compressors. The set comes in a fitted case for organization and protection. The clamp set provides a pair of indicator gauges to measure alignment distortion, with a configurable armature to secure the gauges in position on two axes. The two chain clamps consist of a black anodized aluminum frame with a roller chain that can secure the clamp around a shaft up to 7.5 inches in diameter. The three pairs of 3/8-inch diameter posts measure to 5", 7-7/16", and 9" in length, and are made of stainless steel for rigidity. Two extension plates provide additional radial clearance when needed. Two stainless steel snugs secure one post to another, to hold the gauges in measuring position. The two 81-141J dial indicator gauges have shockless, hardened steel gear trains and low-friction jeweled bearings to withstand excessive vibrations and impact. The three contact points on the gauges are graduated to 0.001", with a total travel range of 0.25". The gauges have a 0.375" diameter stem, a white dial face with numbers ascending from 0 to 50 and descending back to 0, and a rotating knurled bezel to set the dial pointer to the zero position. Clamps are fastening tools that use pressure to secure workpieces to each other or to a workspace, and prevent movement. Clamp style varies widely, depending on general and specialized applications. Many clamps are for temporary use during construction, repair, or alignment of a workpiece, while others may be used to secure a component in its final installation or assembly. The L.S. Starrett Company manufactures precision measuring tools, metrology and testing equipment, and saw blade products. The company was founded in 1880 and is headquartered in Athol, MA. Whats in the Box?