Yes, the Garmin Approach R10 works outside, beautifully. In fact, it is more accurate outdoors than it is indoors thanks to the unlimited ball flight time. When used indoors, the R10 uses a machine-learning model that incorporates inputs from collected radar data to determine the spin. The R10 uses the trajectory of the ball to measure spin when playing outside. If you want to get accurate spin readings, don't put markings such as stickers on your golf balls.