4-corner arms shrink and automatically hold tight your phone. To release your phone press bars to unlock it. One-Hand Operation, Easy to Use. This bicycle cell phone holder designed with 4 corner claws (with a rubber pad inside to avoid scratch), will not crack or break. Display the full phone screen. Phone holder mounts compatible to use with a mountain bike and a road bike. For more convincing you can rotate the phone holder for 360 degrees. Compatible with most bicycle handlebars with a diameter of 25-35MM. Bike phone holder fit for cell phone screen size 4 – 6.8 inches.