【Replace Part Number】The Mulching Replaces: Cub Cadet/MTD/Troy Bilt: 742-05642, 742P05642, Dewalt: DWO1DT233. Please check your original part number before purchasing. 【Package Includes】1 X Mulching Blade. Length: 21"; Width: 2"; Thickness: 0.120 "; Center Hole: 7/8" - Diamond Hole, also Compatible with S-Pattern Blade Spindles; For 21" Mower Decks. 【High Quality】 This blade is made of high-quality steel, which is more resistant. Warm Tips: It is secured under the deck to cut the grass, over time the blade may become dull or damaged causing irregular cutting patterns. Inspect your blades periodically and replace them as needed to maintain a clean cut lawn. 【Fits Models】Fits Cub Cadet: SCP21E Walk Behind Mowers; Dewalt Lawn Mowers. 【Smooth Cutting】The powder coating on the lawn mower blade is dustproof and rustproof, which can a provide long-lasting and reliable support for your mowing work. The sharp blade allows you to cut effortlessly and consistently, ensuring an even and efficient cutting and improving the quality of your lawn maintenance
Specification
Length: 21"
Width: 2"
Center Hole: Diamond Hole,
Deck: 21"

How to install
You would need a wrench to replace it.
1. Make sure to disconnect spark plug before beginning repair
2. Lift the deck to the highest position
3. Remove flange nut that holds old blade
4. Replace old blade with a new one
5. Reassemble and test the mower