78070 manometer 0-7.5 gas valve pressure meter

Manometer used for measuring gas pressure to furnace. Measures from 0 to 7-1/2" inches of water column. Includes 30" long flexible tube, gas valve adapter and magnet at top for holding.To operate, fill large tube with water to zero. Connect flexible tube to gas valve via gas valve adapter. Power-up gas valve and read water level by looking at the smaller tube inside the big tube. That's it!