I'm looking at replacing engine compartment bolts with chromed hex headed bolts. I know there is some sort of kit available that allows you to screw the bolt into various openings to determine the thread width and count, but can't for the life of me figure out what this device is called. Figured it's something Home Depot would carry, but the help there looked at me like I had three heads when I tried to explain what it was I was looking for.