Measures gas pressure, static pressure and pressure differential measure gas pressure on the inlet and outlets with the standard 1/8 NPT fittings or directly with the adapter for wr gas valves take static pressure measurements using the resolution mode of 0.01Inwc read pressure differential measurements across a blower directly includes a easy to use zero function auto power-off (apo) conserves battery life measures pressure between -19.95 and 19.95Inwc (inches of water column) individual P1 or P2 measurements can be made by disconnecting the other port thus referencing the measured pressure to atmospheric pressure kit includes 30′′ tubing, clear hose, tube splice and 1/8 inch NPT brass fitting. Display unit: inches of water accuracy: +/- 1.5% fs (+/- 0.3 inches of water) 0.05′′ water column resolution large lcd display automatic shut off single button operation.