Very small but very powerful,
This review is from: MetroFlash Nocturna USB Rechargeable Taillight with USB Cable
This small tail light for bicycles is very deceptive. Its physical size (approx. 4cm x 2.5cm x 1.5cm, L x W x D) belies the power of its three LED bulbs and L-ion rechargeable battery.
The light can be easily mounted on a bicycle (by using the supplied saddle-post bracket) or a cycle helmet (using the supplied webbing strap) in next to no-time. There are 4 modes of lighting - Super-Bright, Constant, Flashing, or Chasing which can be selected using the push button mounted on the red acrylic lens (this is also the on/off button). I was surprised to find that the flashing modes actually use far less battery than the constant modes (I don't know why but I was under the impression that flashing lights would use more battery power). All fixtures and fittings that may be required to install this light either permanently or temporarily in a position of your choice are supplied in the box (there are nylon cable ties a rubber strap and a webbing strap).
If you need to remove the light whilst out and about it is small enough to fit into your pocket or small bag without being cumbersome.
Re-charging of the battery can be achieved via a USB port on your computer or a dedicated USB wall plug charger. A red light (located just below the on/off button) indicates when the battery is charging, whilst a green light shows that the battery is fully charged. An amber light shows that the battery has roughly 20% charge left in it. I did find the rubber cap which covers the micro USB port (used to connect the charging cable) a little fiddly to pull out but then it does create a waterproof seal and because of the size of the port it is covering it doesn't need to be any bigger.
This is a neat little tail light which should make the cyclist extremely visible to other road users - well worth the money.