Chosen for its reliability, heavy-duty materials and versatility, the 1800 Series has top-rated quality built in for reliable operation and long life. Their great components and features make them the spray heads of choice for a wide variety of applications. Strong stainless steel spring provides reliable stem retraction. Strong stainless steel spring provides reliable stem retraction. Constructed of time-proven UV-resistant plastic and corrosion-resistant stainless steel parts, assuring long product life. Exclusive co-molded wiper seal features an encased plastic "cage" to provide unmatched resistance to grit, pressure and the environment. Pressure-activated, multi-function seal design assures a positive seal without excess "flow-by", which enables more heads to be installed on the same valve. Precision controlled flush at pop-down clears debris from unit, assuring positive stem retraction in all soil types. Two-piece ratchet mechanism allows easy nozzle pattern alignment without tools and provides added durability. All sprinkler components are removable from the top without special tools, providing for quick and easy flushing and maintenance of the sprinkler.