Nutron Collar Double Pro Scooter Clamp

The Nutron 2-bolt collar clamp might be small, but has incredible grip force. The design incorporates a threaded steel insert which means you can tighten the clamp till your heart's content without the fear of stripping it.
The clamp body has material removed strategically to save weight, but keep the high clamp force.

The total weight is just 70g.