These tophat-shaped, blind threaded steel bungs are perfect for making gas tank and oil tank mounts, or for any other fluid filled vessel. Mild steel for easy weldability. These are a slimmer version or our standard tophat bungs, this makes it a bit easier as you can drill a much smaller hole. 1/2" OD with a 3/4" OD flange that is 1/8" thick. The overall length is 1". Featuring a 5/16"-18 thread.