Please check the dimensions and the blade design against your plane (in particular pay attention to style of the grooves - newer versions have a different style of grooves).
The back of the Stanley packet says:
12-220, 0-12 331
Not suitable for: Stanley no 9 1/2G, Stanley no 220G, Stanley no 9 1/2A, Stanley no 220A
No. Of Grooves: 10
Plane Cutter Width: 42mm (1 5/8 inch)
Plane Cutter Thickness: 2mm approx.
Tool Manufacturer: Stanley
We aim to dispatch orders the same day when you order before 9am, Monday to Friday.