[Spool specification]: 30ft replacement line is factory wound for a superior feed. 0.065 inches diameter wearable line supports fast cutting and longer lifetime, compatible with original spools models AF-100.[Professional CNC winding spool]: Compatible with Black and Decker spools by the CNC machine cutting and winding, automatic line change. Manual winding is cumbersome and can easily get stuck during use, which can cause damage to the string trimmer.[Precautions for use]: Wear eye protection and long pants when using this product to avoid injury caused by spilled lines. The product is only suitable for young grasses. For strong weeds, use other tools such as blades to trim.[Rugged material]: High-quality ABS spool & durable polyamide nylon thread, flexible and long service life. Aerodynamic shape allows less drag for more efficient cuts.[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 choose the right spool for your trimmer.