3/8"Sq Drive 16 and 21mm Chrome Vanadium mirror finish spark plug sockets, suitable for 10 and 14mm spark plugs. Rubber sleeved T-Handle Bar is designed to allow maximum leverage to be applied. Ideal for use in confined areas with the 360 Universal Joint. Internal rubber sleeves in the sockets hold and prevent damage to the spark plugs. MOST COMMON SIZES - 3/8"Sq Drive 16 and 21mm Chrome Vanadium mirror finish spark plug sockets, suitable for 10 and 14mm spark plugs. MAX TORQUE - Rubber sleeved T-Handle Bar is designed to allow maximum leverage to be applied. ATTAIN ACCESS - Ideal for use in confined areas with the 360 Universal Joint. HOLD AND PROTECT - Internal rubber sleeves in the sockets hold and prevent damage to the spark plugs.