iBungee & Race-Runners laces alone provide great results for runners at all levels. However, many athletes seeking maximum fit & function step up to Zero-Friction Fittings. Zero-Friction Fittings eliminate friction by raising your laces to the surface of the shoe. Your laces glide easily and amazing things happen. You no longer struggle with uneven lace tension because tension always starts and stays equal throughout the shoe. Laces automatically micro-adjust continuously by adapting to the changing forces and pressures during your stride.