Spark Plug Socket Wrench Set T-Handle Removal Tool Kit 14mm(9/16″) 16mm (5/8″) 21mm (13/16″) for Motorcycles Lawn Mowers Small Vehicles. Wide Compatibility for Small Engines: Designed to fit most motorcycles, lawn mowers, and small motor vehicles, this T-type spark plug wrench supports both 14mm(9/16″) 16mm (5/8″) and 21mm (13/16″) hexagonal spark plugs — eliminating the need for multiple tools in your toolkit.