The spinner is matched up to the plane and not the prop. The Tower Trainer comes with a 2 inch spinner, and that fits a 10 or 11 inch prop.

When you get into cowled planes you will have to match the spinner to the nose of the cowl, and most 40 and 60 sized planes will take a 2 to 3 inch or so spinner.

The only time you will have problems fitting a spinner is when you start using APC props and will need to cut the slot larger.