The Rain Bird 4 in. 1800 Series Spray Head - No Nozzle features a patented pressure-activated co-molded wiper seal prevents wasteful water leakage and assures long life. Heavy-duty stainless steel spring assures flush retraction, every time. Multiple pop-up heights for maximum design flexibility. Wide range of nozzles available (sold separately) for distance of throw and arc pattern. No tools needed to change nozzles. 1/2 inch inlet size.