Relefree&Acirc; Universal Sports Running Machine Safety Safe Key Treadmill Magnetic Security Round Switch Lock Fitness Red Useful New Treadmill safety key:It can work easy and quick on most treadmills requiring a round treadmill safety key. Strong Clip:It can easily clamp to any part of your clothing and it's strong to hold. Size:Cord Length: 81cm,Diameter of magnet shell: 2.2cm,Diameter of magnet: 1.3cm. Fits for most treadmill:Fit to a wide variety of treadmill brands. Good Service:We will solve it well for you if you have any problem.