Mirage Plus Props How Can U Tell If A Prop Is A 21 Pitch I Have A Mercruiser Mirage Plus Prop?

How can u tell if a prop is a 21 pitch i have a mercruiser mirage plus prop? - mirage plus props

the number is marked on the support between the sheets. The number is something like 48-1234-17P
The last two digits of the P enters the field.