Leading Edge Air Foils LLC (formerly Leading Edge Air Foils, Inc.), usually called LEAF, is an American aircraft parts supplier based in Lyons, Wisconsin. It is a US limited liability company. The company was founded by Bill Raisner in Peyton, Colorado, in the 1980s and claims to be the oldest ultralight aircraft parts supplier. The company specializes in the provision of aircraft parts and aircraft engines and in the past supplied kit aircraft for amateur construction and ready-to-fly aircraft under the US FAR 103 Ultralight Vehicles rules.