This Yonex® Muscle Power 2 Junior racquet feature Muscle Power technology with close contact of frame and string ensuring no power is lost on impact and enhances the transfer of energy into every shot. The frame is aluminium with a stiff steel shaft.Frame: Aluminium.Shaft: Steel.Length: 21in.Weight/Grip: 4U (Ave.83g) G5.String Advice: 4U 14-18lbs.