The 1.5 white face of this gauge is easily visible during the day and glows bright in the dark so you can keep an eye on your systems bottle pressure at night. Maintaining system bottle pressure is vital for proper function of the system and its components. This heavy duty stainless gauge measures 0-1500 PSI and has color coded indicators to easily decipher if your system is at the proper pressure. This gauge has a 1/8in NPT threaded stem so it can be attached directly to a bottle valve or any manifold with a 1/8in port.