Ayp OEM Replacement Blade 340-218
FITS MODELS: 20'' WALK BEHINDS 
Mulching blade 
Length 20'' (508mm)
Centre Hole 5/8'' (15.9mm)
Outer Holes 3/8'' (9.5mm) 
Centre 1 7/8'' (47.6mm) 
Width 2'' (50.8mm)
Thickness (3.4mm)