The Sinclair concentricity gauge is engineered for ease of use and exceptional accuracy, distinguishing it as a leading product in its category. Constructed with precision for enduring performance, it accommodates cases up to .50 BMG. This gauge measures runout by rotating the case or loaded round on two sets of bearings housed within anodized aluminum blocks. These bearing blocks are longitudinally adjustable to accommodate various case lengths or loaded round lengths. Users can measure sized cases at the neck and loaded rounds either at the neck or on the bullet. The bearing blocks are positioned within a milled slot on the gauge base plate, ensuring alignment and providing optimal support for the cartridge, facilitating smooth rotation. Large thumb levers on the bearing blocks enable quick and easy adjustments. The anodized base plate offers exceptional stability, ensuring precise readings. The indicator tower allows for vertical and lateral adjustments of the dial indicator. The mounting block is compatible with dial indicators featuring standard 0.375 inches mounts. This tool is an essential instrument for the dedicated precision reloader.