Uses 2 X CR2032 batteries. The LEDs are very bright for its size!
Comes with 2 silicone straps so that you can mount the light anywhere you like.
This is the white light mode. To turn it on/off or switch modes, press the black button in the middle.
By rotating the red plastic piece so that it covers the LEDs, it becomes a red light.
I find that its small size and its ability to switch between white and red coloured lights means that it is very useful as a spare light. If your front or rear light runs out of battery, just use this as a replacement until you get home.
For me, I strapped it around my rear rack, but it will not be switched on normally. In case either my main front or rear light is low on power, I will then use this light as an emergency light if needed. Probably not a good idea to chuck it in a bag as the exposed switch may be pressed accidentally. As it is so small and lightweight, just strap it anywhere on the bike until it is required.