21 mm Pro Plug Socket from Motion Pro.
Features:
- Fits 21 mm and 13/16" spark plugs.
 - Ultra-strong tool steel construction.
 - Slim skeleton profile.
 - Use with a 3/8" square drive or 17 mm wrench.
 - Innovative internal plug retention system.
 - Protective black oxide coating.
 - Easy to read laser etched markings.
 - Can be used as an axle-holding tool on bikes with 17 mm or 24 mm internal hex axles. Through hole allows use of a screwdriver or holding rod.
 - Lightweight.
 - Patent pending.