This innovative TERO AK4 flight system from CUESOUL is well-designed with a combo built-in spring/telescopic and rotation system. Perfect for soft tip and steel tip darts. Features rotation system (without wobbling) allowing each dart to be closely grouped together while avoiding being knocked out when hit by previous dart. The spring/telescopic system prevent dart deflection when flights are hit by previous dart. Both systems ensure flights are more durable for use. This TERO system helps your darts fly more stable and true.