Aircraft Tool Supply Company offers the shop head rivet gauge set. It includes four gauges for -3, -4, -5, and -6 rivets. Each gauge measures minimum height and minimum diameter of shop heads after setting. Eliminates guessing if your rivets are properly set. Works for measuring both universal head and flush rivets. Precision machined to size from 2024 aluminum. Rivet size permanently stamped on each gauge. Color-coded anodized finish. For more information, visit www.aircraft-tool.com or call (800) 248-0638.