The Arctic Hayes U-Flow Water Gauge has an innovative design. The clear, see-through body allows the gauge to be easily read. It has opposing flow-rate measures on each side of the body, so you can measure the flow rate in litres or gallons per minute. This is a vital piece of equipment when preparing a new installation. Simple to read and easy-to-use, this is a must-have for plumbers. Compatible with the 998731 stem thermometer for water temperature testing. Specification: Flow Measure Range: 4-22 litre, 1-5 gallonAdditional Information:Tool Type: U-Gauge