One Colar Fits All Size - The collar measures 28 inchs at most, and can be cutted to any length to fit your pet by using scissors.(Note: Avoid cutting the Led light) 3 Flashing Modes - Fast Flash, Slow Flash, Constant Light, change mode by pressing the power button 1-3 times. USB Rechargeable - The collar is very Eco-friendly. No need batteries, and can be recharged by the USB cable. Safety Necklace - In low light or dark conditions, the LED Light collar can help the vehicles see the pets which can help you keep your dogs safe. Lightweight and Comfortable - With PU materials, soft rubber which can make your pet feel more comfortable.