NSD Powerball Auto Start Pro Indestruction Powerball Perfect for sports (golfers, squash, tennis, fencing, basketball, badminton, archery, cricket etc) fitness, rehabilitation (Carpal Tunnel, RSI, Arthritis etc), all disciplines of musicians, and are great fun too.280Hz Autostart Pro NSD Powerball models are individually hand-assembled with no starter cords required. Induction-powered digital speed meter included as standard.