Glovion LED Wireless Safety Turn Signal Light Vest Safety Gear For Bicycle Biking Night Warning Guiding Light ( Not Include the Backpack) Main function: turn signal for bike riding, traveling, hiking, etc Transmission distance: 3 meters (depending on the surroundings) Battery of the transmitter: 2 pieces of button cells 2032(included) Product Size: 235mm*240mm*15mm ( Not include the backpack) Elastic strap length: 185mm, 300mm(stretched), Weight : 169g