TEKTON 3/8 in. Drive 6-Point Impact Socket Set with Rails (5/16 in.-3/4 in., 8 mm-19 mm) (42-Piece) SID91216 - The Home Depot

The socket's 6-point opening exactly fits the hex nut of the spark plug, so that you can apply maximum torque and loosen stubborn, heat-seized plugs without slipping. Its thin walls and extended deep length allow you to reach far into spark plug wells. The interior rubber grommet inside the socket firmly grips the neck of the spark plug for careful removal and installation. Die-stamped markings are permanently impressed into the steel and can't wear off. They're designed with large, clear size numbers that are easy to read even in low light settings. The polished chrome plating protects against corrosion and wipes clean to a mirror finish. The deepest parts of the socket well, where nickel and chrome layers cannot be deposited in sufficient thickness, are protected with an additional thin layer of clear coat, rather than conventionally-used silver paint, to prevent rust. 4 detent grooves provide a secure connection with the retaining ball of a drive tool. Radiused corners reinforce the drive end x eliminating sharp angles that are prone to cracking under stress. The drive end's beveled edge helps guide a ratchet tang smoothly onto the socket