NIBCO PC601 3/4 PRSXPRS REP COUP(NO STOP) LD.NIBCO? Press System? fittings are the fastest, easiest way to join copper tubing systems in residential and commercial potable, hot, chilled and process water applications for plumbing and HVAC systems. The press fittings can also be installed underground. The NIBCO? Press System? is user friendly, quick and easy to install. When properly crimped a unique “N” witness mark is clearly visible. SSID: 80186