This is a precision set of gages for setting heights, depth mics, and micrometers. These have been checked up to 18 inches with a Cadillac Gage and gage blocks. This set can measure up to 22" total, and 1" increments. The base is a 1" standard and is 4-1/2" diameter, while the other gages are 1-1/2" diameter. These all screw together for different measurements. The sizes are 1", 2", 3", 4", 5" and 6". Everything has been hardened then precision ground.