[Spool specification]: 30 ft replacement line is factory wound for a superior feed. 0.065 inch diameter wear-resistant line supports fast cutting and extended lifespan, compatible with original spools models AF-100. [Professional CNC winding spool]: Designed to be compatible with Black and Decker spools through precision CNC cutting and winding technology, enabling automatic line advancement. Manual winding may result in tangling, which could lead to operational issues or damage to the string trimmer. [Precautions for use]: Always wear eye protection and long pants when operating this product to reduce the risk of injury from flying debris. This product is intended for use on light grass only. For thick or woody weeds, use alternative tools such as blade attachments. [Rugged material]: Constructed with high-quality ABS spool and durable polyamide nylon thread, offering flexibility and long-term durability. 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.