Brompton Derailleur Spring Set with Cable Stop for Overbar Shifters

The Brompton derailleur causes the mechanism to return when the lever is released on a two—or six-speed Brompton.

This is the set, along with the dog-leg section and end stop - for pre-2017 derailleur/trigger systems.

If you're aiming for the full set, which was unfortunately discontinued in 2017, this component should be added to the derailleur cable.