Not much bigger than a quarter
I took it out of the box put it on my water bottle and started using it right away. I purposefully waited to drink water to see what would happen. It’s a bright LED white light that blinks rapidly to alert you that it’s been 30 to 40 minutes since the last time you had a drink. When you take a drink the light blinks slow and low, one time. I think this will work well as long as the bottle is in front of me but if I leave it\go out of the room I obviously wouldn’t be able to see the reminder.
Rating: 5 stars