Rainbird 5000 Series Full Circle Rotor, 4" 4 in. 5000 Series Full-Circle Pattern Pop-up Rotor Heavy-duty cover assembly for extra durability - Rain Curtain Nozzles Slip clutch mechanism for quick adjustment on installation - Heavy-duty retract spring assures positive pop-down 360 Degree full circle arc rotation - Radius adjustment screw allows up to 25% radius reduction without changing nozzles Pressure-activated multi-function wiper seal protects internals from debris and assures positive pop-up and retraction