Purchased 3 of these. They fit well on their Hurta harness. The rubber fitting holds them tight. The lights are bright but not super bright, especially from the side. There is a pointless black trim around the edge of the light that restricts the side visibility. Really not sure why this is included! The spring clip that holds the light to the holder is too weak, meaning they can come of easily if the dogs are playing. Luckily we've not lost one yet but a stronger spring or deeper clip recess would help. Nice range of colours and generally good for spotting the dogs at night but a few things to improve on.