First, Its simple to use imo - it has two circular bands which you can twist to set timer, the upper band is for the total time of tracking say, T (e.g 20 minutes), and lower band is the time remaining when you want the warning alarm/siren to start sound, say e.g you set the lower band to 5 minutes. So you will get a warning sounds (like a quick horn) at, T - 5 = 15 minutes later. That isn’t so hard , is it ? After T = 20 minutes you get another sounds/siren to indicate time off. It starts to blink with yellow light after warning time, i.e at T = 15 minutes in this example. The light is green when you set the alarm, and its red before you start the timer ( just turned on mode but not in use). You can adjust the sound volume.Also want to mentioned it takes 3 small batteries ( AAA I think, just confirm)My use case - Its not only for kids, I am an adult and I am using it everyday, I will mention my example how it is helping break one of my bad habits. So I used to spend a lot of time in restroom in morning, mostly browsing quora, Facebook and other news apps while doing big job and then pondering what I read during shower, wasting almost an hour and eventually missing my trains and not be in office at time I wanted to be. I deleted bunch of apps like Facebook which helped for a while but eventually I found something else to waste time. I carried phone with me as an excuse to be aware of time, check my schedule for the day etc. I tried using phone timers, alarms etc none of which actually worked because none had a way to warm me. So solution really was to not carry my phone with me but still get my time tracked and something with a warning so I can be time bound and rush up when warning sounds. I looked for a solution and luckily I found this.Now I don’t take my phone with me, just this mini tracker, set it to 20 mins with a 10 minutes warning and to my surprise I am all ready before 20 mins most of the times lately and able to shut it off before the final warning kicks in (after 20 minutes).The only concern some might have is this that the minimum unit of time is 5 minutes and you can't be more granular than that. This company has some more digital time tracker products which you can set at minutes/seconds level but I really wanted something very simple to not distract myself and it really fits my use case.As some of reviewers mentioned it to be a cheap quality, its actually not for the price.Overall I am very happy with this product and will highly recommend it. I have just started to use it so will update how it turns out in long run in terms of product lifecycle.