When I first started using the light, I was pleased that I could turn it on and keep it on all the time. Once I got my plants at a point where I knew they needed the dark to rest, that's when I started using the timer. The timer started to work perfectly at first. However, when I made an adjustment to it and was moving it around, it became unplugged. Once I plugged it back in, the timer never worked the same again. It is difficult to get it turned on again, it's as if there is a short in the switch because I can’t get it to turn on with out several attempts because it turns off immediately. Once I do get it turned on and set to 9 hours, it will turn itself off like it is supposed to, but it will not turn itself back on again. So, I have to struggle to manually turn it on every day which wasn't the point of the light. I can't return it because I no longer have the box It came in. I'd hate to have to buy another one because the light actually works, the switch is just a pain to use. I can't keep it on 24/7 because then my plants would suffer. Everything else about it is fine. It has a good strong clamp and the lights adjust very easily. If it weren't for the switch and timer, I would have given it 5 stars.