about this product: Suitable for: Fits most trimmer models: S TC1820, STC1815, ST4525, ST5530, STC1820PC, EPC, STC1840, EPC, ST1823 etc. Quality Edger Line: 9.15m edger line can achieve larger mowing range with 1.65mm dia. polyamide nylon is durable and flexible. It is not easy to break, which ensures continuous work. Quick and clean cutting: The replacement spool of the automatic feeding system facilitates the tedious work of manual winding spools. It uses centrifugal force and aerodynamics to reduce drag and make fast, clean cuts. Perfect replacement spool: They are a perfect replacement for most stock & spool models such as AF-100 , AF-100-3ZP, AF-100-BKP. The coil can be inserted and removed without tools, and the operation is simple. At the same time, damage to the device is avoided and the thread is used optimally. Great value set: the package includes 6 spare trimmer spools, 1 spare cap and 1 spring spare. Coil cap replaces RC-100-P cap, spring replaces RC-100-P spring. Excellent value. Note: The data is all manually measured, please allow 1-3cm error, due to the difference in light and display, there will be a certain color difference, the actual object received shall prevail.