331737B Mulching Blade, 21-Inch Professional Lawn Mower Blade for Craftsman, Husqvarna, Poulan Mowers, Replaces OEM no. 165833, 175052, 406712, 532175064, 594893001, 175064

What It Is

The 331737B is a 21-inch mulching blade designed to chop grass clippings into fine particles that decompose quickly, returning nutrients to your lawn. It’s intended for professional-grade residential mowing on Craftsman, Husqvarna, and Poulan walk-behind mowers with a 21-inch cutting deck.

Fitment & Compatibility

Before buying, confirm your mower deck measures exactly 21 inches (center hole to blade tip). This blade replaces OEM part numbers 165833, 175052, 406712, 532175064, 594893001, and 175064. It fits many Craftsman, Husqvarna, and Poulan models from the 1990s onward, but verify your specific mower’s model number against the manufacturer’s compatibility list. The blade has a 1-inch center hole and a 7-point star drive pattern—measure your spindle’s center hole and drive shape to ensure a match. If your mower uses a different hole size or drive pattern (e.g., 5-point star or round), this blade won’t fit.

Key Things to Know

• Quality: Heat-treated steel with a corrosion-resistant coating; holds an edge well but may dull faster on sandy or rocky soil compared to premium aftermarket blades.
• Installation: Easy DIY job with a socket wrench and blade removal tool. Torque the bolt to 35-50 ft-lbs—overtightening can strip the spindle.
• Common gotcha: This is a dedicated mulching blade, not a bagging or side-discharge blade. If you switch between modes, you’ll need a different blade for each.
• Balance: Always check blade balance after sharpening or installation; an unbalanced blade causes vibration and spindle wear.

Should You Buy It

Buy this if you own a compatible 21-inch Craftsman, Husqvarna, or Poulan mower and want a reliable, affordable mulching blade for fine clippings and healthier grass. It’s a solid value for residential use, but skip it if you need a universal blade or a heavy-duty option for commercial mowing.