This is a Tuned Pipe that fits a .40-.45 Sized Engine. FEATURES: Made of Aircraft Grade Aluminum Quiets/Muffles Engine Exhaust Increases the Power and RPMs of the Engine INCLUDES: One 7.5cc (.40-.45cu in) Tuned Pipe REQUIRES: Exhaust Adaptor (header) to fit the specific engine Coupler SPECS: Overall Length: 12-3/16" Diameter (at widest point): 1-1/2" ir/jl