it is too easy to press the button by accident. The buttons should have stronger spring mechanisms.Dunno how long the battery will last, it was on when it arrived, still on today, a month laterQuit working during a light rain. After drying out it worked again.First time I used the product and the unit was never held beneath the water, the unit only got wet and yet the unit stopped working almost immediately. You can see the water still trap in the unit the next day. Water-Proof relates to not letting water into the device up to 96 ft of water pressure. This unit let water in by being one-time dunked for less than five seconds in five feet of water.False Advertising is the key to this product. The product is not Waterproof or Water Resistant - it is just poorly made. Do not waste your time nor your money buying this product.I spent about 45 minutes working with this stopwatch. It has some very useful features for sports timing. I primarily got it for the countdown timer for timing my elliptical trainer sessions.When I received the stopwatch, it was turned on. I am wondering how much charge is left in the battery for it to arrive in this state. The product description states that a protective film cover should be removed from the LCD display. I looked carefully and couldn't find one.I started by setting the time and date. That worked well on first try. However, when I advanced to other modes, I found the clock would reset automatically to its default value (2018). Sometimes the screen would go completely blank for about 20 seconds and then come back on. It had a mind of its own.I tried both the count up and count down timers. I also tried the pace time. All of these worked for a while but, again, the screen would go blank and it would reset.The instruction sheet is fairly straightforward and easy to understand. What is missing is whether the battery can be replaced and how.At this point i am wondering if the battery is almost dead given it arrived in an "on" state.The instruction sheet states "If you have any issues and trouble with our product please contact us via email." However, no email address is given.I rarely give one star reviews but given these issues, this stopwatch is not useable for me. I can't recommend it. Other reviewers have had better luck with it. It's possible I received one that had been used (no protective cover on LCD) and/or the battery is worn out. It also may be just poor quality control.Update - Important Please Read - April 24, 2022The seller saw my original one star review and sent me a replacement watch. This one works as it should. I upgraded my rating from a one star to a four star because of this. It would have been a five star review if not for the issues I went through. Hopefully, your experience will be better.Priced at only $15, this sports stopwatch includes all the usual features. It measures to the thousandth of a second, records up to 10 splits, has a pacing feature, memory, and alarm. The instructions are understandable as well, and the button layout is intuitive. My son is starting his track season this month, and this watch will be handy for me to use when recording his race times and relay splits.I have been a time caller for the local marathon for many years and I have seen a variety of stop watches. This one I bought for myself because the others did not really meet my needs. Some would be too sensitive and the time would get reset in the middle of the race or some would not hold up if it started to rain and some were digital and could be hard to read in bright sun. This one covered all those bases and more so it gets 5 Stars from me and made this yearly event a bit less stressful for me.This stop watch actually has some pretty nice features for the price.Those include:Standard day/date time modeAlarm clock modeChronograph mode with 10 lap memoryCountdown Timer (appears to max at 9 hours, 59 minutes, 59 seconds)Pace mode (You can set an interval and the unit will beep and keep track of every 1/X divisions of a minute - up to 1/320).Everything is controlled by the four buttons on the watch.3 o'-clock position - Mode button to switch function2 o'clock - Start/Stop button12 o'clock - Recall button. To recall lap times, etc in each mode10 o'clock - Lap/Set/Reset - Increment laps/Set time/date/alarm/number of pace divisionsOverall a nicely featured stop watch for the price.