Blue Lug original, Koma lights.
You could easily install the light on pretty much any part of your bike.
They are very tiny little lights, but the battery lasts for maximum of 20 hours, and can be recharged with an USB cable.
The name "Koma"(Spinning Top) comes from a classic Japanese toy which looks very simular to the product.
Light color：Red (rear)
Work time : about 8 hours to about 20 hours
Power : about 20 lumen
Light modes : steady, flash
USB chargeable (about 2 hours)
Outer diameter：about 3cm
Comes with M5, M6 bolts