Simplicity OEM Replacement Blade 345-108
Requires 2 for 36'' deck; hi-lift blade 
Length 18 1/2'' (469.9mm)
Centre Hole 3/4'' (19mm)
Outer Hole 3/8'' (9.5mm)
Centre Hole 2 9/16'' (65.1mm)
Thickness .187'' (4.7mm)