John Deere mower blade kit GY20850 — OEM replacement blades for 42" decks, factory-balanced fit

The John Deere Original Equipment Mower Blade Kit GY20850 is a direct-fit replacement blade set designed to restore cutting performance on compatible John Deere lawn tractors and mower decks.

This OEM blade kit replaces worn or damaged blades on a wide range of John Deere models so your deck cuts evenly and reliably. Manufactured to John Deere specifications, the kit is intended to match original balance, hole patterns, and blade geometry for proper clearance and consistent grass discharge. Use this kit when you need factory-fit parts that maintain deck performance after long seasons of mowing or when switching between mowing and snow attachments.

Which John Deere models will this blade kit fit?

The GY20850 kit fits many John Deere riding mowers and lawn tractors across several series. Check your owner manual or blade part reference to confirm compatibility before purchase.

• Fits series: 102, 105, 115, 125, 135
• LA-series decks: LA100, LA105, LA110, LA115, LA120, LA125, LA135 (42" decks listed)
• Also compatible with D100, D105, D110, D120, D125, D130, X125, X145 models
• Works with multiple snow blade and 2-stage snow blower attachments on listed LA/D models

How does this blade kit affect cutting performance?

Replacing blades with the OEM GY20850 set restores the deck's designed cutting geometry for cleaner, more even cuts. Properly balanced, sharp blades reduce scalping, improve bagging/side-discharge efficiency, and lower stress on spindle components.

• Factory-balanced blade profile for minimal vibration
• Maintains original discharge and mulching characteristics
• Reduces uneven cut lines and tearing of grass blades

What should I know about installation and maintenance?

Installation is straightforward for anyone comfortable with basic mower maintenance; however, always follow safety steps and torque specifications from John Deere. Regular sharpening, correct mounting orientation, and periodic balance checks extend blade life and protect the deck.

• Install with engine off, spark plug disconnected, and mower secured
• Observe original blade direction and torque bolts to factory specs
• Sharpen as needed and replace if bent, cracked, or excessively worn

Are these blades suitable when using snow or collection attachments?

Yes — this OEM kit is listed as compatible with a variety of snow blades, 2-stage snow blowers, and collection systems for the same John Deere models. Using the correct blades helps keep attachment clearance and deck balance correct while switching between tasks.

• Compatible with 42" and 46" snow blade applications noted for LA100–LA125
• Listed for 44" and 42" 2-stage snow blower configurations on multiple models
• Works with collection systems specified for LA100–LA130 series decks

Who is this for: Lawn owners and equipment technicians who need an authentic John Deere blade replacement to preserve factory cutting performance on specified compact and lawn tractor models. If you own a listed model and prioritize correct fit, balanced operation, and compatibility with seasonal attachments, this OEM GY20850 blade kit is built to meet those needs.