SLOPE METER INC. Manufacturers of instruments that "Help you made the Grade" for over 60 years. Slope meters are accurate to 1 degree with a 1 second response. 3.5 x 8.5 x 1" Size. Aluminum cast. Used to determine "percent of grade" and is calibrated to read from .00 to .12 (0-12%). The "No. 2" aids the operator and speeds work on motor graders, asphalt pavers, wheel ditches, tunneling machines, and other equipment where exacting specifications are required