Grasscool D130 42 inch Mower Mulching Blades for John D-eere D110 D100 D125 D105 S100 E100 LA125 LA115 LA105 42'' Deck Lawn Tractor Riding Mower Replace GY20850 GX22151

What It Is

These are aftermarket mulching blades for 42-inch cutting decks on select John Deere lawn tractors. They replace OEM part numbers GY20850 and GX22151, designed to chop clippings finer for nutrient recycling rather than bagging or side-discharge.

Fitment & Compatibility

Check these before buying:

• Deck size must be exactly 42 inches – measure from blade tip to blade tip across the deck. This set is not for 38", 46", 48", or 54" decks.
• Fits these John Deere models: D100, D105, D110, D125, D130, S100, E100, LA105, LA115, LA125. Also compatible with certain S120/S160/S180/S240 (verify deck size). Not for X-series or older tractors.
• OEM cross-reference: Replaces GY20850 and GX22151. Confirm your current blade has these numbers stamped on it.
• Measurements: Blade length is 21.25 inches, center hole is 1 inch diameter, thickness is 0.1875 inch. If your existing blade matches these, they’ll fit.
• Not for: Zero-turn mowers, push mowers, or any deck other than a 42" stamped or fabricated deck.

Key Things to Know

• Mulching vs. standard: These are true mulching blades with a curved, angled shape and extra cutting edge. They will not bag or discharge well. If you switch between mulching and bagging, you’ll need a second set.
• Installation difficulty: Moderate. Requires a socket or wrench to remove the blade bolt (usually 5/8" or 15/16"). Use a torque wrench to tighten to 40–50 ft-lbs. Always block the blade or remove the spark plug wire for safety.
• Balance check: Grasscool blades are usually balanced out of the box, but it’s worth verifying with a blade balancer before installing. An unbalanced blade vibrates and can damage the spindle.
• Sharpness: They come sharp but not razor-sharp. For best mulching performance, sharpen after 10–15 hours of use, especially on tall or damp grass.

Should You Buy It

If you own a compatible John Deere 42-inch deck tractor and primarily mulch your lawn, these are a solid, budget-friendly alternative to OEM blades. They work well for average-sized yards (under 2 acres) and hold up decently for the price. Avoid them if you need to bag or side-discharge regularly, or if you have a different deck size.