This item wears due to the abrasive stream, more quickly if nozzles and air jets are not changed promptly (abrasive flows around nozzle, cuts a groove in the power head and stops siphon gun from working). Our power head is manufactured from Zamac, a harder material than aluminum for longer life, and has a case hardened steel insert for better fit against back side of the nozzle. The result is long life and powerful suction. Includes medium steel nozzle, air jet and gasket. 3-3/8" long, 3" high, 1" wide. Made in USA.