Brompton Airtag HolderBrompton Airtag Holder The "Brompton Airtag Holder" is designed to fit the original Brompton bike saddle. It attaches securely underneath with a threaded hole specific to Brompton seats. Before buying, make sure your seat has this threaded hole, as it won't fit other types of cushions. This case is for storing an AirTag under your Brompton saddle discreetly.