Stahlwille extra deep Spark Plug Socket have 3/8in drives and rubber inserts. They are made from HPQ® high performance quality steel and chrome plated. THe sockets have an extremely high load capacity with exceptionally thin rings and walls. They are free from cadmium and therefore suitable for use on titanium alloy parts and titanium fasteners, such as those used in the aerospace industry, where saferty is crucial. The sockets are equipped with anti-slip drives to permit high transmission of forces to the lands of the nuts and bolts without damaging them. MADE IN GERMANY.Stahlwille Spark Plug Socket Rubber. Size: 18mm (11/16 in).