Fits most Black Decker af - 100 - 3zp lawn mowers, suitable models: gh400, gh500, gh600, gh610, gh900, gh910, st6600, st7000, cst1000, cst1200, cst2000, mtc220, mte9120, nst 180.0 , nst.1118, nst2118, lst200, lst300, lst420, lst136.[Automatic Feed Spool]: Black and Decker Weed Eater replacement spool is easy to use and automatically feeds the trimmer by centrifugal force, reducing the cumbersomeness of manual sorting to replace the trimmer line spool at work.[abrasion resistance]: Black + Decker weeder cutting ropes are made from a modified nylon polyamide material that provides tensile strength of over 100 pounds, 30% durability compared toother brands and a longer lifespan.[efficient cutting]: Black & Decker's trimmer spool line is flexible and variable, allowing the line to stretch and cushion impacts on hard surfaces, increasing cutting efficiency by 50% and allowingwith each reel to cut more weeds.[easy installation] the spool installation process is very simple, just place the replacement spool on the lawn mower, install the spring on the threaded cover, then install the threaded cover on the spool.Easy installation, quick replacement, saving time and effort, high flexibility and high reliability.