Webstone 44443PR 3/4-Inch IPS Isolator EXP E2 Tankless Water Heater Service Valve Kit Includes a residential pressure relief valve (150 PSI/200,000 BTU) 500 WOG 4444 series - IPS Union x IPS Compact version of Webstone's original Isolator EXP Certified to NSF/ANSI 61-8