Fits String Trimmer Models: CMCST900, CMCST910, CMESTA900, CMESTE920 and CMCST98020. Compatible Model: Our replacement trimmer spools are compatible with -CMZST065 and CMZST0653. Cap Cover Model: CMZST120SC. Strimmer Line: Premium about 30 feet in length and 0.065 inch in diameter. The trimmer spool line cuts through grass and weeds easily. Allows less drag for more efficient cuts. Pliable and flexible allowing the line to stretch and cushion the impact with hard surfaces. Auto Feed Trimmer Spool: High quality ABS and polyamide nylon spool, flexible and long service life. The trimmer replacement spool uses centrifugal force and aerodynamics to reduce drag, achieve a clean cut, and uses centrifugal force to feed the trimmer line as needed. The auto-feed system replacement spool makes the tedious work of hand-wound spools easier. Pre-wound, ready to use: Each replacement spool comes pre-wound and can be easily replaced in seconds. It is very easy to assemble and remove, you can snap it