Don’t get stuck at red lights waiting for the signal to change. This strong magnet will help identify your bike at a traffic light when there is an inductive loop system in the road to cause the lights to change. This magnet will not harm on-board electronics. Measures 4 1/8” x 9/16” x 1/2”. It easily mounts with 3M adhesive tape and wire ties. Works on any bike or trike. Single.