I had been using some of the older and larger shot timers that have been on the market for many years, but I decided on the SG Timer GO for its smaller form factor that still features a large display. The buzzer is very loud and the sound sensor/microphone is very sensitive and can be used for dry fire practice as well as live fire.The display is excellent for readability and being back-lit, it is easy to read in any lighting condition. Construction is solid, the two buttons (start/stop and a mode change button) are easy to use and work well to navigate the SG Timer Go's various operating modes. 3 modes come pre-programmed (Live Fire, .22 and Airsoft/Dry Fire) which can be modified to your specific requirements via the SGT Smart Phone App which pairs with the timer via bluetooth.Using the associated SG Timer smart phone application you'll also be able to access custom features/drills, score matches, record video that overlays the times of any shots detected in the video, edit or add additional operating modes and change parameters like shot detection sensitivity, echo suppression, buzzer volume, buzzer delay, number of shots in a string, number of consecutive strings, etc. Check the manufacturer's web site for a great series of instructional videos on all of the SG Timer Go's various features.One very cool way to use the smartphone app (iOS and Android versions available, I've only used the iOS version so can't comment on the Android version specifically) is that you can use your smart phone as a remote control for the SG Timer Go as long as you're within Bluetooth range and any shots detected will show simultaneously on the timer itself as well is within the app. Very handy.Excellent device with very powerful capabilities in a compact form factor. A really good value.