Honda OEM Replacement Blade 305-0609
520mm, nore 18,5mm
Right hand blade 
Length 20 9/20'' (520mm)
Centre Hole 3/4'' (18.5mm)
Outer Hole 11/32'' (8.75mm)
Centre 2 9/16'' (65mm)
Width 2 3/8'' (55mm)
Thickness 5/32'' (4mm)