PLUG ONLY GAS CYL VALVE SAFETY POL

A "PLUG ONLY GAS CYL VALVE SAFETY POL" is a safety plug for old-style liquefied petroleum gas (LPG) cylinders with a Type 21 (POL) valve. Using this plug is recommended for safety when the cylinder is not in use, especially during transport. It helps prevent accidental gas leaks by blocking the valve opening and is part of the older safety standards, as new cylinders use a different, safer LCC27 valve.