If you have lost your treadmill safety key or you simply want to purchase a spare, you can buy one directly from LifeSpan. These square prong replacement safety keys for treadmills work with the following LifeSpan products: TR800-DT5 Treadmill Desk TR1200-DT5 Treadmill Desk TR5000-DT5 Treadmill Desk TR800-DT7 Treadmill Desk TR1200-DT7 Treadmill Desk TR5000-DT7 Treadmill Desk