The Lisle Line Socket 21mm is a great tool for any mechanic or DIYer. This line socket is designed to quickly and easily remove and install fuel lines, heater hoses, and vacuum lines. It features a 1/2" drive and is made of chrome vanadium steel for durability. The 21mm size is perfect for most applications and the socket has a knurled head for easy gripping. The Lisle Line Socket 21mm is a must-have for your toolbox!