AC04029 Replacement Mower Blades 20 in for RYOBI 40V Brushless Cordless Lawn Mowers RY401018 / RY401170 / RY401017 / RY401180, Center Round Hole with Half-Moon & Square Hole

What It Is

This is a set of replacement 20-inch mower blades designed for select RYOBI 40V brushless cordless lawn mowers. They feature a center round hole with half-moon and square hole patterns, making them direct-fit replacements for specific models.

Fitment & Compatibility

Before buying, confirm your mower model is on this list: RY401018, RY401170, RY401017, or RY401180. These are 20-inch blades—measure your current blade length end to end. The center hole is round (approx. 1/2") with a half-moon notch and a square hole for alignment. OEM part number is AC04029. These are aftermarket but match OEM specs. Check that your mower uses a single blade (not dual or mulching-only design). If your model isn’t listed, measure your blade’s hole pattern—round with half-moon and square is uncommon on other RYOBI mowers.

Key Things to Know

• Quality: Made from hardened steel; reviews average 4.0/5—some report shorter lifespan than OEM, but acceptable for regular use.
• Installation: Easy with a socket wrench. Use a blade stopper or block of wood to prevent rotation. Torque bolts to 30-35 ft-lbs (check your manual).
• Common Gotchas: The half-moon notch must align with the mower’s drive pin—if it doesn’t, the blade won’t sit flat. Also, these are for 40V brushless models only; do not use on gas or 18V RYOBI mowers.
• Sharpness: Blades come unsharpened (as most replacements do). You may need to sharpen them before first use for best cut quality.

Should You Buy It

This is a solid, budget-friendly option if you own one of the four listed RYOBI 40V models and want a direct replacement without paying OEM prices. It’s right for DIYers who don’t mind basic installation and occasional sharpening. Avoid if you need OEM durability for heavy use or have a different RYOBI mower model.