Yonex Muscle Power 33 light is an another edition to the Muscle Power series. Muscle Power 33 Light locates the string on the rounded archways that eliminate stress-load and fatigue through contact friction. This construction creates total unity of the string and frame through closer and tighter contact. The Muscle Power series, with its unique frame construction, integrates the frame and the string like no other. The series is designed for players who go after fast movement and effortless power