Brompton handlebar catch In 2003 Brompton introduced this handlebar catch, which has to be used in conjunction with a new nipple. Both are supplied as part of this kit The catch is also fitted with a spring This is one of the "Brompton Essentials" - a part necessary to keep your Brompton folding as it should. In a properly set up Brompton, the final part of the fold should be to undo the clamp holding the stem into place and the handlebar assembly will drop down and clip into the catch automatically. It's made of a tough plastic/nylon material - sometimes over time this can become brittle and break. (Breakage is also more likely if it's not quite set in the right position to allow a clean fold) It is used in the final part of the fold ... Let the handlebar stem drop, and be caught / clamped securely