A single half watt LED supplemented with two standard LEDs powered by two AAA batteries and all wrapped up in a well sealed case is a recipe for a good rear light.
But if we add to that a case that glows fairly brightly too, then that recipe just gets a little better. There are two brackets supplied, one for the seatpost and one for the seatstay of the frame. Both require a Pozidrive number 2 screwdriver to fit them, but once installed they're solid and stable and allow the light to be clipped on and off the bike with ease.
Although the packaging states the light is UK compliant, this is not to be confused with being legal in the UK. There are two modes of operation, and as one is flashing and the other is constantly on, then because the light is not BS approved and is an LED capable of being on constantly, the daft UK Road Vehicle Lighting Regulations make it illegal unless used as supplementary lighting to a legal set-up. Which is clearly bonkers, as this is a great little light for a great price. To buy, its code name is LAM317R.