Rypstick radar, works great. No know issues. ACCURATE: Unlike other radars, there is no need to hit a ball; the RypRadar is designed to accurately measure club head speed by swinging your Rypstick, Driver, or Iron NO-CONTACT: Accurately measure your swing speed without a ball with your Rypstick, Driver, or Iron IMPROVE YOUR GAME: Drastically improve your golf game with RypRadar; HIT LONGER DRIVES AND SHOOT LOWER SCORES FEEDBACK IN REAL-TIME: RypRadar displays swing speed after each swing, saves data from your last 10 swings, and provides optional voice feedback BATTERY-POWERED: RypRadar measures speed in MPH and KPH; 5 AA batteries included. SAFE: Meets safety and FCC Standards; please read RypRadar instructions carefully before using