This is a high-lift side discharge lawn mower blade for AYP, Craftsman and Husqvarna riding mowers, OEM part number 173920 (compatible with 532173920 / 138498). Made of durable steel with a black anti-rust coating, it features a 5-point star center hole and fits most 42-inch cutting decks. The high-lift design creates strong airflow to expel grass clippings efficiently, making it ideal for cutting tall, thick or damp grass.