Husqvarna OEM Replacement Blade 340-157 
FITS MODELS: 20'' walk behinds 
Mulching blade 
Length 20'' (508mm)
Centre Hole 5/8'' (115.9mm)
Outer Hole 3/8'' (9.5mm)
Centre 1 7/8'' (47.6mm)
Width 2 1/4'' (57.2mm)
Thickness .134'' (3.4mm)