Netafim Self Piercing Pressure Compensating Emitters w/ Internal Check Valve - 1.0 GPH Black (25 pieces/Bag): The Netafim Self Piercing Emitters have a sharp barb, making them easy to install, no tools required. These emitters have a 1.74 PSI internal check valve that helps prevent low emitter drainage holding back up to a 3.9 ft column of water. The anti-siphon operation prevents contaminants from being drawn into the emitter. The Self Piercing Emitters are pressure compensating and deliver the same flow from 10.15 to 58 PSI. Exclusive TurboNet flow path design regulates flow and provides continuous self-cleaning action during operation. Recommended minimum filtration of 120 mesh.