Smart Distance Pro is the extended set of Smart Tools® collection. This rangefinder (telemeter) measures the distance to a target using camera perspective. The effective distance is 10m-1km. It can be very useful to golfers, hunters and sailors. To measure the distance, you should know the height (width) of a target. Don't worry!! Man's height is 1.7m(5.6ft), a golf flag is 7ft, a bus is 3.2m(10.5ft), a door is 2.1m(7ft). We can guess the height (width) of almost everything. Furthermore, if you know an airplane model, you can measure the altitude of flying airplane. For reference, Boeing 747's width is 72 meters. Usage is simple: Input the height (width) of the target, and touch the screen. If the target is aligned by 2 green lines, get the measured distance. * 3 tools for distance were completed. 1) Smart Ruler (short, touch) : 1-50cm 2) Smart Measure (medium, trigonometry) : 1-50m 3) Smart Distance (long, perspective) : 10m-1km Smart Speed (speedometer) calculates the speed by the distance and time moved horizontally. Usage is simple: Enter the shortest distance to a target. Measure the shortest distance in advance with a rangefinder (e.g. Smart Distance, Smart Measure, Map). Then, touch your screen following the target. If the result is not accurate, you can calibrate your device with the [Speed Calibration] option. For more information, watch YouTube and visit the blog. Thank you. * It is a one-time payment. The app price is charged only once. ** Smart Tools package does NOT include what is in this app. ** No internet support : You can open this app without any connection. After installation, open the app 1-2 times with your device connect to WI-FI or 3G/4G.