At the top of the spark plug nuts are hexagons, namely 16, 18 and 21MM Material: The spark plug wrench is made of high-quality stainless steel, which is stable and can be used for a long time Use: This spark plug wrench is always suitable for this in an automotive workshop, agricultural machinery workshop or small appliance workshop 720 degree adjustable: Easy to install and remove spark plugs even in tight spaces Note: If the universal spark plug wrench is used for a long time, oil will leak out. It is recommended to check and clean the spark plug from time to time