Husqvarna 537338701 Trimmer Head Bump Knob Genuine OEM AYP Part American Yard Products manufactures parts and equipment for leading brands in the industry. Those include Craftsman, Husqvarna, Poulan Pro, Poulan, Weed eater, Roper, Sears, Rally, EHP (Electrolux Home Products) and Yard Pro Fits: T25 Trimmer Heads (2005-01), (2007-04)