This is the Injector Air Valve set for the OS Max FS91 Surpass II FI. It takes the place of the original carburetor to allow for electronically controled fuel metering by way of the EC-2 unit and an injector. FEATURES: Aluminum Construction Electronically Controlled Fuel Injection INCLUDES: One Assembled 60T Injector Air Valve unit One Gasket O-ring Two 3x24mm phillips-head mounting screws REQUIRES: Cannot work without EC-2 electronic unit SPECS: Length: 15.9mm (.625") Width: 44.5mm (1.75") Height: 31.8mm (1.25") Throat mounting diameter: 12mm (.47") COMMENTS: This Air Valve Set for use on the FS91 SurpassII-FI. NNA 7/22/02 ir/kh