I recommend anyone who is interested in purchasing weedeater line for thier weedeater to consider using square line.  I just recently purchased an aftermarket weedeater head that uses two short precut pieces of line.  I now use .80 square line on it.  Although the square line may be a bit more pricey you can find great deals on it on ebay and IT IS WORTH IT.  What would normally take nearly an entire spool of string I can now do with 2 to 4 short pieces.  I can now edge areas with it that I couldn't even make my electric edger work well on.  So there may be more cost involved at the initial purchase but it will last you much longer than normal line.