This is a rear bike light which is made by CatEye. It has 3 red LED lights within it which produce 25 lumen. It is USB rechargeable and comes with a micro USB cable for convenience and can therefore be connected up to a power bank, computer or phone charger to charge it up easily. The batteries are included in it. It has four light modes which means that you can choose the one that is most suitable for the conditions that you are riding in. There is also a light mode memory function. There are seat post bands included and a bracket can be purchased separately if needed.