I use a tour 90 and i use a laserfiber MS200TT. I use prince lightning xx and dunlop max comfort 17 guage at 54 lbs tension . i have a friend who also uses tour 90 . he used to play with kevlar coz he is a string breaker and developed some shoulder and elbow problems . i did string his racquets (2 tour 90's) a week ago with technifiber e-matrix 17 guage at 55 lbs and he only used it for about 3 hours of play and it broke (string) at the middle of the stringbed. then after 2 days he let me string both tour 90's with sensation supreme 17 guage at 54 lbs . these strings id say lasted 4 hours and in both racquets , the string broke between the 3rd and 4th hole at the head. i am very careful when i string and in my racquets i have about 8-10 hours of play on them and they have not broke yet . i am wondering about where his strings broke between the 3rd and 4th hole - if i made any mistakes , or if a string breaker can break strings in this location.i wanna know the causes so i can do better next time . also i want to know what strings you can recommend for my friend. tnx a lot and i hope you have some ideas for me .