Replacement Trimmer Spool: Replace your worn-out spools with our premium 0.065" dual line trimmer line spools, ensuring your trimmer performs at its best. Compatible with Greenworks: Designed specifically for compatibility with Greenworks models 2101602, 2101602A, STBA40B210, ST40B410, BST4000, these spools offer a seamless fit and function. Flexible and Long Service Life: Crafted from high-quality ABS spool and durable polyamide nylon thread, our spools provide enhanced flexibility and a long service life. Aerodynamic Shape: The aerodynamic design ensures more efficient cuts, saving you time and effort in your gardening tasks. Easy Installation: Our spools are easy to install and come in a convenient 8-pack, providing ample replacement options for your trimming needs. Upgrade your trimming experience with our precision-engineered dual line trimmer line spools, designed to meet the demands of professional-grade use while offering the convenience of auto single-line feed for effortless operation.