Stiga OEM Replacement Blade 305-0669
Mulching blade 
Length 20 9/20'' (520mm)
Centre Hole 7/10'' (18.5mm)
Outer Holes 2 9/16'' (65mm)
Centre 2 3/8'' (55mm)
Width 11/32'' (8.75mm)
Thickness 5/32'' (4mm)