The Reotemp Home Water Pressure Test Gauge is a pressure gauge designed for quick and easy pressure monitoring in the home. The 3/4" hose connection screws onto any standard hose or faucet. Featuring an easy-to-read dial, the marks clearly show 0-160 PSI. The red max pointer allows you to record spikes in pressure when you are away from the gauge. Just adjust the red max pointer to rest above the black pointer before testing your pressure. When the gauge reads pressure the black hand will drag the red max pointer and the pointer will record the max pressure seen on the gauge. To reset the max pointer, just turn it down to zero above the black pointer and test again.