Simply set the dial, turn on your water and walk away. It measures gallons or approximate minutes and can be set for automatic shut-off at any point up to 700 gallons or 4 hours. Includes manual on/off settings and a slow shut-off feature protecting hose and plumbing from damage. Minimum flow rate is 2 GPM for proper operation and works with water pressure ranging from 15 PSI to 120 PSI. The flow rate may vary depending on water source and sprinkler used and may not work with small irrigation systems. Attaches to any standard faucet, hose or sprinkler with a swivel nut for easy connection.