You are looking at a:
Manifold Pressure Line Manometer Gauge Set:

Gas LPG Propane Line Low Pressure Test Diagnosis Tool Kit 15 inch Water column

You are looking at a:Manifold Pressure Test Kit: Analog 0 to 15" of Water Column (Model: GPK15) w/Case, Tubing & Brass Adapter Measure Natural gas (methane) or LP gas pressure across appliance manifolds. Test gas stoves, furnaces, dryers and other gas appliances. Can also be used for other non-corrosive gases. This is a National Safety Product. Features:
*Large 2½" sensitive diaphragm gauge is calibrated in inches of water column, also shows torr(mm Hg)
*Magnified lens for easier reading
*Easy to use, just attach the brash adapter to the appliance and hook the tubing to it and read the pressure.

Specifications:
*Range:0 to 15 inches of water column (in. H2O) , 0 to 28 mmHg (torr)
*Supplied with: 2½" sensitive diaphragm gauge; 3' of rubber tubing; brass fitting to connect to the appliance manifold port(1/8" NPT); a plastic carry case for easy carrying and storage.
*Never run out of battery!!! because you do not need it.
*Never need to mess up with water in glass tubing and guess if the column is plumb!
*As precise as your eyes can read the analog dial.

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