This is the O.S. 90° Exhaust Adapter #873 OSMG2835 and the #873S OSMG2958 Mufflers This gives you the flexibility of pointing your muffler up or down. They are ideal for many helicopter installations, where standard muffler mounting is impossible. FEATURES: Natural aluminum construction INCLUDES: One 90° Muffler Adapter Two 3x16mm black steel cap head screws w/.5 pitch threads Two 3x35mm black steel cap head screws w/.5 pitch threads REQUIRES: A 2.5mm hex wrench to install SPECS: Distance between mounting hole centers: 37mm Length: 15.4mm (engine to muffler) OS EnginesPart OSM25425500