Boeing MD80/90, B717 Bypass Pin with Remove Before Flight Flag and Lanyard.
Aircraft bypass pins are used to bypass hydraulic system steering on aircraft, allowing for steering to be controlled completely by the pushback tug. Failure to use a bypass pin when the hydraulic system is activated can lead to equipment damage and operator injuries, as well as damage to the aircraft. Since some aircraft cannot bypass hydraulic steering without shutting down the entire hydraulic system, a bypass pin saves time and makes towing easy.
Each bypass pin is made of high-strength steel and the kit comes with a bright red flag with the words “REMOVE BEFORE FLIGHT.” The flag is fitted to the pin with a heavy-duty clip and lanyard.