Compatible with Black and Decker models: GH3000 LST540 GH3000R LST540B,easy to choose the right spool for your trimmer Easy Installation: simply push this trimmer head into the string socket and it automatically locks in place with assistance from the side push buttons SF-080 Trimmer blade head can be used to trim edges,heavy grass removal.tidy up large bushes,small wood and small shrubs Wear eye protection and long pants when using this product to avoid injury caused by spilled lines After-Sales Assurance: Pls contact us first when you get some problem, we will offer you assistance asap THTEN SF-080 Trimmer Blades Head Spool Line Compatible with Black & Decker GH3000 LST540 GH3000R LST540B Edger Grass Trimmers 24+4+1