Motion Pro, Pro Plug Socket™ 21mm Spark Plug Socket for Harley Davidson

21mm socket, fits most spark plugs with 14mm thread.
Use with a 3/8″ drive or 17mm wrench.
Allows for fixed or angled swivel operation up to 15° when used with the optional 567325 Swing Out Extension Bar.
The swing extension is used to gain better (angled) access to hard to reach places.