Larger quanes offer better discounts Instructions for use: Press the switch to turn it on, then short press to change the brighess, long press and hold to switch to flashing mode Hold down the switch and don't let go. When the light becomes dim, immediately let go and the light will turn off Product Name: Bicycle USB Charging Ultra Bright Tail Light Packing: 20 pieces in one small box, 120 pieces in the whole box Mode: Six flashing modes Weight: 0.1kg Waterproof function: The product can be immersed in water for a long time.