Mtd OEM Replacement Blade 335-715
FITS MODELS: For 20'' decks; 1997 and newer; fits bow tie stle centre hole 
Mulching blade
Length 20'' (508mm)
Centre Hole 1 x 3/4'' (25.4mm)
Outer Hole 5/16'' (19mm)
Centre Hole 2 1/2'' (63.5mm)
Width 2 1/4'' (63.5mm)
Thickness .134'' (4.2mm)