This is the Builder's Protractor.

FEATURES: Ideal for any task requiring precise angle measurements.
          Measure right thrust on R/C airplanes: Hold the angle finder on the
            thrust washer and measure the angle to the left side fuse. Flip
            the tool over and measure the angle to the right fuse side. The
            difference between the two readings is the thrust angle.
          Measure down thrust on R/C airplanes: Block the tail so it is level.
            Block up the protractor so it is parallel with the table and line
            up the pointer with the thrust washer. The reading will tell you
            the amount of down thrust the engine has relative to the tail.
          Car modelers can use the Builder's Protractor to set caster/camber
            angles and toe-in (remove the short end of the pointer).

INCLUDES: One Plastic Builder's Protractor

SPECS:    Length: 8½" (216mm)
                                                                    JXS 5/10/00
                                                                          ir/jl