Got this for my dog Jac - Jac is a small dog (jack russell x shihtzu)
This flashing collar was a bit too big for Jac - you can trim it up to a point but it would have been loose so instead I kept it at the size it was and we doubled it up around his neck (still loose but a tight enough fit). Jac didnt seem at all bothered by it and was happy to wear it for several hours in the house.
This collar has bright red led lights - there are 3 options (1) fast flash (2) slow flash (3) permanently on - you move through these options by pressing the on off button - if you press it again (4) it turns the collar off.
The collar has a built in re-chargeable battery which is a fab feature - you charge it via a usb cable which is supplied - you can either use it with a computer/laptop or with a standard usb plug.
Jac is pleased with the collar - we wish it came in a smaller size though :)
NB I received this item at a discount in order to give my honest review and feedback. Words opinions and pictures are my own and based on mine and my dogs experience using this product.