the one grim makes is the same as a huey, but bigger. i have several different guages,but i use the one from grim alot more. it also has a chart that comes with it.
I've got one of Grim's prop gauges,as well as a Hughey,a Frank Orlic and a Little Rock Welding unit. They all work differently and they all have good and bad points,but they are all helpful tools.