What is the real swingweight of the Microgel Prestige Mid plus? On TW the swingweight is 320 but on the USRSA site they rate it 304. I'm really confused about this. I don't know anymore what I must believe about these ratings. What is the correct one? I guess the USRSA rating is more realistic because I played with the MGMP and it felt lighter than I supposed. Can anyone explain these different ratings?