With this app only, you can display lap time measurement using GPS, display speed and logging. With the external Bluetooth GPS DG-PRO1, it is possible to measure very high precision and trace the line.　You can buy DG-PRO1 from amazon.co.jp https://www.amazon.co.jp/dp/B07LGQKXF6/ref=cm_sw_em_r_mt_dp_U_WLCjCbBRS89HM # When measuring lap time with app only 1. Open Drogger settings. (Please swipe down the meter screen. The gear mark at the top of the screen is "Drogger settings".) 2. Select [L