Here is a video of the Hosford gage. You need Adobe Flash player. Part Two is on the right, scroll until you see it.
A video is much easier to understand than words in my opinion.

Most all will work, the Hosford is a great tool to use at a show providing it is not to crowded and the seller lets you do so.

http://www.youtube.com/watch?v=1jQZn4kohH4&feature=relmfu


David