BJ Enterprises Leak-Guard Tank Gauge is a visual, interstitial-space tank gauge that is ideal for detecting leaks in double-wall tanks. The large sight gauge will indicate with a highly-visible orange indicator if a leak occurs in the interstitial space, with a 4-window glass display that is easily read from any direction. This unit comes with a nickel-plated brass chain that is field-adjustable to 72 in depth from the top of the tank, though an extension chain is available, and the gauge features a 1-1/2 NPT threaded tank fitting. The Leak Guard gauge can also be combined with a Wall Mount Sentry or 007 Tank Monitor to provide audible and visual interstitial leak detection.