Double Line Automatic Feeding System -- The trimmer replacement spool is compatible with the FLYMO FLY021 thread trimmer. The automatic feeding system replacement spool eliminates the tedious work of manually winding the thread trimmer and the extra time and effort required.<br> Durable Materials -- The strimmer line is made of durable ABS spool and premium nylon line,which keep the spool line stable while using the grass trimmer,hard-wearing and cutting grass faster.<br> Spool Specifications -- High-quality weeder rope with 11m/36 FT weeder replacement line, 1.5 mm/0.06 inch in diameter, which can easily pass through grass and weeds.<br> Compatible With Most FLYMO FLY021 Trimmer Models -- Such as CONTOUR 500 xT, POWER TRIM 500 XT, MINI TRIM AUTO ST/XT/PLUS XT, MINI TRIM CONTOUR XT, SPEEDI-TRIM, CONTOUR, CONTOUR 500/700, MINI TRIM AUTO/AUTO, MULTI TRIM 250D/250DX/300D/30D, POWER TRIM (PNC 9648641), POWER TRIM 500/700 (PNC 9648596/7) REVOLUTION 2000/2300/2500 AND TWIST AND EDGE.<br> Sincerely For You -- I believe in investing in good products, so they last longer. If you want the best quality and great customer service, please choose us! If you have any questions, you could feel free to contact us at any time. Your satisfaction is our greatest affirmation.