Quick verdict
If you want the classic alternating-stripe lawn look and already own a compatible Ryobi walk-behind mower in the 20-21 inch range, the Ryobi ACLS01 Lawn Striper Kit is a practical accessory to evaluate. It's listed at USD 75.95 and comes in used condition, which is the main thing to weigh before buying.
Who it suits
This kit is aimed at Ryobi walk-behind mower owners who want a striping solution without switching equipment. The listed compatibility covers several Ryobi models from RY401170 through P110, and the 21-inch dimensions match mowers with a 21-inch deck. If that's your setup, this accessory is designed to pair with your mower without needing another brand's parts.
What stands out from the listed details
The ACLS01 is described as a high-quality accessory designed specifically for Ryobi walk-behind mowers. It has a 21-inch diameter and length, and its compatibility list includes Ryobi models RY401170, RY401017, RY401180, RY401018, RY401260, RY401026, P11100, and P110. The striping kit works by creating alternating light and dark stripes as you mow, giving your lawn a striped, manicured appearance.
Meaningful trade-offs
The most important trade-off is condition: this unit is listed as used. Even a used striper kit can show wear, so you'll want to examine the roller and mounting hardware before relying on it. The fit is also specific: it's built for Ryobi mowers in the 20-21 inch range, so if you have a different brand or a larger deck, this kit won't match your equipment.
Product note
Ryobi ACLS01 Lawn Striper Kit for 20 In. - 21 In. Mowers

This kit's 21-inch roller is sized to match Ryobi walk-behind mowers with 20 to 21 inch cutting decks. The compatibility list spans Ryobi models RY401170, RY401017, RY401180, RY401018, RY401260, RY401026, P11100, and P110. The main limitation is the used condition, so set aside time to check the roller, brackets, and general wear before your first mow.
Bottom line
If you own one of the compatible Ryobi 20-21 inch mowers and want a striping kit without paying for a new unit, the Ryobi ACLS01 is a reasonable option. Just factor in the used condition and confirm your mower is on the compatibility list before ordering.