Rain Bird 1804 4" Pop-up Sprinkler Spray Head Exclusive co-molded wiper seal features an encased plastic "cage" to provide unmatched resistance to grit, pressure and the environment. Precision controlled flush at pop-down clears debris from unit, assuring positive stem retraction in all soil types. Strong stainless steel spring provides reliable stem retraction. Two piece ratchet mechanism on all models allows easy nozzle pattern alignment without tools and provides added durability. Pre-installed orange 1800 Pop-Top flush plug blocks debris from entering after flushing. Allows for easy nozzle installation.