HARMAN HARMAN Gas Plug for Gas Cock JG-100C - Model: JG-100C - Type: Gas Plug for Gas Cock - Brand: HARMAN - Accessories: Instruction Manual Brand new, unused, and unopened! Thank you for viewing. I work in the gas-related industry. This is a product from about two years ago, although the year of manufacture is unknown. It's a part that attaches to an old-style gas cock to connect a gas cord and a fan heater. It has been stored indoors in a cool, dark place, so I believe there is almost no deterioration.