NIBCO PC607 2 1/2 PRESS X PRESS 90 ELBOW.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.