Manfrotto FF3236 Double Carriage with Brake (#0923)

This is provided with a brake on only one carriage. Normally, the carriage with the brake is mounted on the fixed rail so that it is locked into place enabling the mobile rail to slide. If the carriage with the brake is mounted onto the mobile rail, you obtain the opposite effect, that is, the sliding of the mobile rail gets blocked, while the carriage can freely slide on the fixed rail.