Netafim Self Piercing Pressure Compensating Emitters with Internal Check Valve, Black, 1.0 GPH - Pack of 1000Self Piercing Emitters Pressure compensating, self flushing emitters with a check valve and self piercing barb for easy installation. 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