Automatic Feed Spool: Weed wacker string replacements for Ryobi weed eater is easy to use, automatically feeds the trimmer by centrifugal force, reducing the trouble of manually sorting the replacement trimmer line spool during work. Abrasion Resistant: Trimmer string replacements for Ryobi weed eater is constructed with upgraded nylon polyamide material that has a tensile strength of over 100 pounds and is 30% more durable than other brands for a longer service life. Cutting Efficiency: The weed trimmer string for the weed eater replacements for Ryobi is soft and flexible, allowing the line to stretch and cushion upon impact with hard surfaces, and increase cutting efficiency by 50%, allowing each spool to cut more weeds.