Compatible with Multiple Trimmer Models: This replacement spool is compatible with Ryobi ONE+ cordless trimmers (18V, 24V, and 40V). Auto-Feed Spool: The trimmer replacement line is easy to use and automatically feeds the trimmer by centrifugal force, reducing the need to manually sort the line while working. Abrasion Resistance: The trimmer replacement line is made of upgraded polyamide nylon, providing over 45kg tensile strength and durability. 30% better than other brands, for longer life. Cutting Efficiency: The trimmer replacement line is soft and flexible, allowing the line to stretch and absorb impact against hard surfaces. Cutting efficiency is increased by 50%, allowing each spool to cut more weeds. If you want the automatic feed to work better, the recommended solution is to apply powder to the spool, which will provide a small amount of lubricant.