Oregon Tool® 91-509 - 20-1/2" Lawn Mower Blade

Blade Width - Measure near the center of the blade.
Thickness - Measure near the center of the blade.
Blade Length - Measured diagonally from the corners of the blade
Center Hole Size - Many blades will have a round hole in the center of the blade and you will need to know its diameter. Blade Length 5 or 7 Point Star Center holes may be 5 or 7 point star shaped. 5 point star on blade7 point star on blade Square or Rectangular The MTD built blades on many walk behind lawn mowers have a 'bow-tie' hole. In this case the Oregon replacement blade will have a rectangular center hole which will fit on the bow-tie pattern on the blade adapter. Square or Rectangular hole on blade MTD Blades The MTD™ built blades (Bolens, Cub Cadet, Troy-bilt, White, Yard Machine, and Yardman) may have a 6 point star. Oregon replacement blades will have a 'Y' shaped center hole which will fit exactly on the 6 point star on the blade spindle. 6 point star for MTD blades The two sizes of the 6 point star. If your blade spindle has a bolt and lock washer that holds the blade to the machine you would use the 11/16" star or 'Y' blade. blade spindle with bolt and lock washer. If your blade is secured with a large flange nut then you would use the 5/8" star or 'Y' blade. blade spindle with large flange nut
OffSet - (Sometimes referred to as offset): If you set the blade on a table this is the distance the center of the blade is above the table top (if any) when the cutting edges are flat on the table
Air Lift - Air lift is the distance the lift panel rises above the cutting edge.

Fit Guide
Dixie Chopper: 3360, 3372, 5018, 5020, 6024, LP3000-60, LP3000-72, LT1800-34, LT1800-44, LT2000-50, LT2000-50D, LT2300-50D, LT2500-44D, LT2500-50D, LT2700-60D, LX2000, LX2000-42, LX2001, LX2001-42, LX2002-42, LX2400, LX2400-42, LX2401, LX2401-42, RT2760, SE2550, SE2750, SE2760HP, SP2800-60, SP2800EFI-60, Whiz-Mow, X2000, X2000-50, X2001-60, X2002-50, X2200-50, X2202-50, X2303-50, X2400, X2400-50, X2500-50, X2502-50, X2503-60, X2703-60, XCD66, XCD74, XF2200-50, XF2200-60, XF2500-60, XF2600EFI-60, XFG2700-50, XFG2700-60, XG2503-50, XG2703-60, XG2703-72, XT3200-60, XT3300-60, XT3300-72, XWD3500-60, XWF2700-60, XWF3000-60, XXG2703-72, XXWD3500-72
Hustler: Super Z, XR-7, Z

Replacement Guide
Dixie Chopper: 1057718, 112947, 30227-60, 30227-60E, 30227-60H, 30227-60L, 30227-60N, 30227-60T, 30227-60V, 30227-60X, A30227-60N, A60227-60N
Dixon: 12421, 12451, 12508, 13368, 13869, 13870, 13921, 13922, 13956, 13957, 13958, 13960, 539119871, 9383
Hustler: 600901, 602771, 602771X, 603992, 603992X, 793794, 793794X, 793794Y, 793935, 793935X, 794214, 794214X, 794230, 794230X, 794230Y, 794685, 794685X
Jacobsen: 30227-60X
Mowmore: DC6441
Prime Line: 7-04572
Rotary: 6441
Sunbelt: B1DC1506