[Spool specification]: 30ft replacement line is factory wound for a superior feed. 0.065 inches diameter wear-resistant line supports fast cutting and longer lifetime, compatible with original spools models AF-100. [Professional CNC winding spool]: Compatible with Black and Decker spools through precision CNC machine cutting and winding, enabling automatic line change. Manual winding may cause tangles and potential damage during use. [Precautions for use]: Wear eye protection and long pants when using this product to avoid injury from flying debris. This product is designed for light grass trimming. For thick weeds or heavy vegetation, use appropriate tools such as blades. [Rugged material]: High-quality ABS spool and durable polyamide nylon thread provide flexibility and extended service life. Aerodynamic design reduces drag for more efficient cutting performance. [Compatible with Black and Decker models]: GH400, GH500, GH600, GH610, GH900, GH912, ST6600, ST7000, ST7700, CST1000, CST1200, CST2000, MTC220, MTE912, NST2018, NST1118, NST2118, LST220, LST300, LST400, LST420, LST136. Easy to select the correct spool for your trimmer.