I've been playing with an AeroPro Drive racquet and RPM Blast strings for the last four years. I always buy an entire reel of RPM Blast. I've noticed that their durability varies quite drastically. Today, for example, I played for only an hour with a newly strung racquet before my strings broke (this has happened to me before on about 3-4 occasions). I don't believe it's the fault for my grummets. The strings from this reel typically only last between 6-10 hours. I also noticed that my strings invariably only break on top of the racquet, but that's maybe because I put about 14 gr of lead at 12 o'clock. In any case, I'm getting to the point where I'm thinking that I need to change strings entirely and go with something else, because of this poor durability.