Compatibility：This spool (Model #2900719) and spool cap (Model #2958002) are only compatible with select Greenworks 40V string trimmers, including the following models: 2101602, 2101602A (BST4000), 2103002 (ST40B410), 1301202 / 1366502 (STBA40B210). Not compatible with Greenworks 24V, 60V, 80V, or other non-40V models. Please check your trimmer's model number before purchasing. Important Note: Dual-line trimmer caps are NOT universal，These parts will NOT fit for other Greenworks models. Please check the model number on your trimmer, not just the line size. — Usually located on the label near the motor or battery port — before placing your order Professional Styling - Our replacement caps are green round caps with a diameter of 2.95in and a cap height of 1.265in. Our spool cap cover is designed to hold the spool in place securely and correctly, ensuring that your trimmer works as it should Made of High Quality Materials - PA66(Nylon)+G30(Glass Fiber). Adding just the right proportion of glass fiber to the nylon material not only dramatically increases the stiffness of the caps, but also enhances wear and heat resistance, effectively extending their life. This is a feature not found in other ABS plastic caps How to confirm the suitability of your lawn mower - you can find the model code in the product nameplate on the head of your lawn mower; you can check the instruction manual of your lawn mower to find out the model number of your lawn mower; in addition, we provide presales consulting service for our products Friendly Reminder: Ordering the wrong model may cause trimming issues. If you're not sure, please contact us before purchasing! This is a Chway brand string trimmer replacement trimmer string, model number 2900719,Compatible with Greenworks string trimmer. This product will fit the following string trimmer models: #2101602, #2101602A, #STBA40B210, #BST4000 Please make sure that your string trimmer model number matches the model number in this list. If you are unsure of your lawn mower model, check the item nameplate and manual of your lawn mower for your model number. Different models of string trimmers require different replacement caps, so make sure you choose the right product. This product is of reliable quality and has been carefully designed and manufactured to ensure that it is a perfect match for your lawnmower, thus providing you with an efficient, reliable and long-lasting experience.