Mulching Blade Replacement for Craftsman 21-inch Cutting Decks CMXGMAM1125499 CMXGMAM1125500 CMXGMAM1125501 CMXGMAM1125502 CMXGMAM1125503 CMXGMAM1125504 CMXGMAM1125505 Lawn Mower

What It Is

This is a replacement mulching blade designed for Craftsman 21-inch cutting decks. It chops grass clippings into fine particles that settle into the lawn as natural fertilizer, eliminating the need for bagging.

Fitment & Compatibility

Check your mower’s model number against these compatible Craftsman models: CMXGMAM1125499, CMXGMAM1125500, CMXGMAM1125501, CMXGMAM1125502, CMXGMAM1125503, CMXGMAM1125504, and CMXGMAM1125505. Measure your existing blade – this replacement has a 21-inch cutting width, a 1-inch center hole, and a 0.25-inch thickness. It fits most Craftsman 21-inch walk-behind mowers with a 7-point star or 5-point star spindle pattern. Verify spindle compatibility by counting the points on your current blade’s center hole. If your mower uses a different pattern (e.g., oval or diamond), this blade won’t fit. Aftermarket blade – not OEM Craftsman, but meets OEM specs.

Key Things to Know

• Installation difficulty: Easy – requires a socket wrench, torque to 30-40 ft-lbs, and a blade removal tool (or wood block to jam blade). Always disconnect spark plug first.
• Mulching vs. bagging: This blade is optimized for mulching. If you bag or side-discharge frequently, consider a standard blade instead.
• Sharpness: Comes sharp but dulls faster than OEM on sandy or dirty lawns. Resharpen or replace every 25 hours of use for best results.
• Balance check: After installing, spin the blade by hand. If it wobbles or vibrates, remove and re-torque. Unbalanced blades damage spindles and cause uneven cuts.

Should You Buy It

Buy this if you have a compatible Craftsman 21-inch mower, primarily mulch your clippings, and want a cost-effective replacement that works as well as OEM. Skip it if you need a bagging or side-discharge blade, or if your mower uses a non-standard spindle pattern.