Kobalt Universal Metric 3/8-in Drive 6-point 21mm Spark Plug Socket

Retainer holds plug by the insulation for better grip. Specialized socket design works on multiple types of fasteners including 6-point, 12-point, square, star, spline and most rounded. Constructed of chrome vanadium steel and heat treated for strength and durability. Natural surface grind finish with a matte black finish that allows you to easily identify the tools in your tool box. Size callout is laser etched. Meets or exceeds ASME specifications. Hassle-free lifetime guarantee.