Spark Plug Socket - 18 mm - Socket can be driven with various tools including the Motion Pro® spark plug ratchet wrench, 3/8" ratchet, 13/16" wrench, tool kit bar, or a Phillips screwdriver placed through the 8.5 mm hole at the top of the socket - Originally designed for the Honda XR400R as a trail tool but fits many models with 18 mm plugs - Thin wall design to fit into low clearance plug cavity