Gas cocks are shut-off ball type valves commonly used in installation of residential and commercial appliances and heating equipment such as gas stoves, fireplaces, water heaters, boilers, furnaces, etc. They are compatible with natural, manufactured, liquefied petroleum gas (LPG or propane) or air mixtures of such.
Round / square needle valve
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A needle valve is a type of valve having a small port and a threaded, needle-shaped plunger. It allows precise regulation of flow, although it is generally only capable of relatively low flow rates.