What is muscle technology? I cannot see, the dark side clouds all I apparently have it on my sl-70, I don't notice any difference between this racket and my old one which didn't have it. My strings don't really move or roll. Explainations? Master Yoda
If you mean the Yonex muscle power technology - it's the rounding off or arching of the part of the frame where the string passes thru between grommets. It's suppose the relieve stress and prevent the string from moving around. On higher end MP racquets, they also use special grommets on the shared holes.