Rotax Piston Ring Spanner (compressor)

How does one know in advance which 912 piston size they have to buy the correct Spanner size? Will a generic Spanner from a kit work on a Rotax?

If you go on the Rotax Service centers home pages just look up the piston ring compressor for the 912.

https://www.leadingedgeairfoils.com/912-914-series-repair-tools-3.html

#36 in the diagram.