The term 'GAS TANK COVER' can be summarized as a CAP that is used to cover the opening of a gas tank. This CAP is typically made of metal or plastic and is designed to protect the contents of the tank from dirt, debris, and other contaminants. It also helps to prevent fuel from evaporating and keeps the tank sealed. The CAP is usually secured with screws or bolts and is often marked with a warning label.