The Craftsman 3/8 inch drive spark plug socket is high quality and versatile. While you can spend less money for spark plugs in this size range, you don't want to skimp on quality just to save a few bucks. From servicing lawn mowers to weed whackers to vehicles, this spark plug set covers all of your bases. The Craftsman spark plug socket set features the following sizes 5/8 inch 13/16 inch 3/4 inch and 18 mm.