1Fitment: The magnetic swivel spark plug socket is a replacement for 1 Series E81 E87 N43B, for 3 Series E90 N43B, for 5 Series E60 N43B.2Unique Design: 360 degree swivel action for maximum flexibility in a tight area. And magnetic core effectively retains spark plugs and minimizes damage.3Magnetic Swivel: The interior magnet retains and protects the spark plug, not easy to loose the plug when installing and removing, more convenient and efficient.4Premium Material: Hardened and heat treated chrome vanadium alloy steel and chrome plated mirror finish maximizes longevity of abrasion and resists against rust and corrosion.5Important Parameter: The size of this magnetic swivel base is 14mm, the size of the driver is 3/8in, with a 12 point design, which is much thinner and fit s perfectly for operation.