Omega Technologies OM2-1522HST-2 Large Diameter Hi-Lite Protrusion Gauges, 4PC Set. Omega Technologies 4PC Set of Precision Protrusion Gauges for large nominal diameter Hi-Lite® fasteners in sizes 7/16”, 1/2”, 9/16”, and 5/8”. Measuring 1 5/8” square, these Omega Technologies Precision Protrusion Gauges are easy to handle and provide plenty of reach to inspect larger fasteners. Omega Technologies Precision Protrusion Gauges are made of etched, full-hard stainless steel that insures a long gauge life. This Omega Technologies Protrusion Gauge Set comes on a chain for easy manipulation and storage.