DOCAS 21 inch Mower Mulching Blades for 42" Cut, 742-04308, 2 Pack | MTD Compatible, Cub Cadet Compatible, Troy-Bilt Compatible, Replaces 742-04308, 742-04312, 942-04308, 942-04312

What It Is

This is a 21-inch mulching blade set (2-pack) designed to fit 42-inch cutting decks on select MTD, Cub Cadet, and Troy-Bilt lawn tractors and zero-turn mowers. It replaces OEM part numbers 742-04308, 742-04312, 942-04308, and 942-04312, and is intended for mulching grass clippings into fine particles that decompose quickly.

Fitment & Compatibility

Before buying, confirm three things:

• Deck size: Your mower must have a 42-inch cutting deck. These blades are 21 inches long each, and two cover the full width.
• Center hole & spindle fit: Check that your spindle uses a 5-point star center hole (common on MTD-style decks). Measure the center hole diameter—typically 1 inch—and the blade thickness (about 0.25 inches).
• Model cross-reference: This set fits most MTD, Cub Cadet, and Troy-Bilt models that originally used 742-04308 or 942-04308. Verify your mower’s model number in the product listing or with the seller. Not all 42-inch decks use the same blade pattern—some use oval or offset holes.
• Aftermarket note: While these are aftermarket blades, they are designed to match OEM specs. If you need exact OEM, stick with Cub Cadet branded parts.

Key Things to Know

• Mulching vs. bagging: These blades have a higher lift and curved design to recut clippings. They will not work well for bagging or side-discharge without swapping blades.
• Installation difficulty: Moderate. You’ll need a socket wrench, torque wrench (40–50 ft-lbs recommended), and possibly a blade removal tool. Always disconnect the spark plug first.
• Balance check: Aftermarket blades can be slightly off-balance. If you notice vibration after install, remove the blade and balance it with a cheap blade balancer.
• Durability: Made from hardened steel, but expect to replace them every 2–3 seasons depending on lawn size and debris. Sharpen or replace when edges round.

Should You Buy It

Buy this set if you own a 42-inch MTD-family mower (Cub Cadet, Troy-Bilt) and primarily mulch your lawn. It’s a solid aftermarket alternative to OEM blades at roughly half the cost, with good reviews for fit and cut quality. Avoid if you need bagging blades or have a non-MTD deck pattern.