I'm using the LoNoiz .130-Inch-by-150-Foot Spool Commercial Grade Spiral Twist Quiet 1-Pound Grass Trimmer Line, Black LN130DLG-12
It's fantastic, except it does fray at the ends after awhile. So it occurred to me that maybe I should try the old nylon rope trick of melting the ends shut using a lighter. Did that yesterday. Now comes the test!