In grams unstrung.. He is top 20 in his agegroup in his country., strong, tall but a bit lanky because of his age. One handed backhand, Dimitrov like strokes.. He has used 290gram Yonex frames the last year, with some light customization, swingweight 310(was 304, but likes 310 more) total weight now is 319 grams, dampener and overgrip included... most players his age use 285 grams rackets, but at what age is it ok to move up to the 300gram range? if he likes it of course, i was thinking maybe in one og two years but what do you think?