Like a few other reviewers have stated, the product is simply broken. I thought I'd give it a try since some others apparently had success, but I definitely didn't. I have tried a few times to get it working but it always resets itself in 1-3 days.EDIT: So customer support contacted me and it was probably the best experience I've ever had with support from any company. I had already returned the unit but in order to test their new units they sent me 3 for free. I obviously wouldn't expect that from support, but if you call support they should return the one amazon gave you and give you a new one.The problem seems to be with fluorescent lights (In my case aquarium lights). I have 3 aquariums that I wanted to be on a timer but they emit an interference that causes the timer to reset. If this is the application you are going to use it for then I wouldn't hesitate to purchase it as customer support will be very willing to replace your unit by sending you a new model(that is resistant to the interference) and a free return shipping label for the old one.These are great timers that work much better than mechanical timer counterparts as you can be much more precise with your time selection, while having many more options. I also found mechanical timers to not keep extremely accurate time. If they are both on par exactly, in about a month they will be 5 minutes apart...but not with these digital timers. My 3 aquarium lights have been turning on and off within a second of each other for about the past week. It's great to not have any of them straying off in their light up times.