Superior quality heat muffs are made entirely of 6061 & 5052 aircraft grade aluminum, offset from the center to clear the close cowling of most homebuilts. Install anywhere on exhaust system where there is 12" of straight 1 3/4" exhaust pipe. For effective cabin heat you must have forced air, thus design utilizes air forced through the muff. Use for either cabin heat or carb heat or both. Interior baffle slows air passage, increasing heat output. Muff is split & piano hinged to clamshell over the exhaust pipe for easy installation. Weight w/clamps is 12 oz.