This is an Incidence Meter is for Setting Proper Thrust, Wing and Stabilizer Incidence on Model Airplanes or is Used to Determine Why a Model is Not Flying Straight. This Will Work On All Model Airplanes with Wing Chords of 15.25" or Less. Robart offers an extension for large wings, but we don"t carry it(see COMMENTS) FEATURES: Magnified Window, Anti-Parallax, Jeweled Movement Scale Meter. Reads Within 1/8th of One Degree. Bearing Mounted Pointer With Mirrored Surface Behind For Easy Viewing Steel Counterweight Bubble Level A Must For Building True and Straight Airframes No-Slop "V-Block" Clamps INCLUDES: One Model Incidence Meter Two "V-Block" Clamps One 18-1/16" Long Parallel Bar One Instruction Booklet REQUIRES: Assembly of Incidence Meter. COMMENTS: Robart does make a 36" Parallel Bar part 404029M (we do not carry it, but they will sell directly to the public). ir/jl BOX DIMENSIONS: 6.50" W. X 1.50" H. X 18.50" L.BOX WEIGHT: .46 LBS.