This is the Great Planes Builder's Protractor.

Features:

• Ideal for any task requiring precise angle measurements
• Marked in 1° increments and attached to a handle that doubles as a 4" (100 mm) ruler
• 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 small section of swing arm that extends below protractor)

Includes:

• One Plastic Builder's Protractor
• Length: 216 mm