Aluminum 3mm spool line Brush Cutter Cutting String Trimmer Head Replacement Trimmer Brush Cutter head replacement , the shaft hole size is 15 mm , and up blade hold circle is 25.8 mm. 4 fixed nylon cutting line with M10 1.25 METRIC FLANGE NUT AluminumTrimmer head is more lightweight and more non-friable than Nylon head designed for heavy duty brush cutter systems of 30cc Fits 99 % mm of grass trimmers, includes Ryobi, John Deere, Echo, Stihl, Homelite, Bolens, Weedeater, Craftsman, Toro, Cub Cadet, Troy Bilt, Poulan, and most other makes. It has good durability and safety. It's not going to fit with Craftsman 25cc 71137 and 71147.