The Grainger Approved Therma Level Gauge HDPE is a high-density polyethylene level gauge designed for use with water heaters and boilers. It features a clear, shatter-resistant tube with easy-to-read level markings and a 3/4 in. NPT lower connection. The level gauge allows visual monitoring of system water levels and can handle temperatures up to 250°F. It is made in the USA and measures 18 in. long with a 2 in. OD tube. The HDPE construction provides chemical resistance. This level gauge helps indicate when to add water to prevent dry firing.