Aircraft Wiper Arm. NSN 2090-00-402-2176. Hamilton Standard p/n LE721139-20. United Technologies p/n LE7211139-20. Cooper 12713-90. Used on helicopters and supersonic aircraft. Would be neat on a street rod or custom car. 20 Inch Length. More Specs: UB Hole Diameter 0.390 inches nominal AAUH Spline Minor Diameter 0.587 inches minimum and 0.591 inches maximum AAUJ Spline Major Diameter 0.676 nominal mils and 0.680 nominal centimeters ABSA Spline Quantity 36 ACHZ PIN Mounting Hole Diameter 0.130 inches nominal APCS Adjustability Nonadjustable AWKH ARM Length 20.000 inches nominal BBJX Mounting Position Universal BJYP Painted Feature Not included BJYQ Drive Adapter Extension Included BJYR Drive Adapter Extension Type Integral BJYS Blade Mounting Method Pin or saddle BJYT Drive END Mounting Type Spline BJYW Drive END Drive Shaft Mounting Hole Included L4A6 10344