Can I upgrade my Classic with the PRO2 components?

If you want to enjoy the increased capacity/added perks provided by the PRO2 brew head, you can upgrade your Classic if it is PRO-enabled: To check if it is PRO-enabled, confirm that there is a black, plastic adaptor ring sat on the red portafilter holder. This piece would be removed when using the larger PRO2 parts. 

Note you will need to purchase the complete Full PRO2 Brew Head to make this upgrade, even if you already have a Pressure Gauge set-up for your Classic (as the sizes are different). This kit will include everything needed for the switch, including the larger size PRO2 stem, plunger, dosing cup/tamper, and funnel - in addition to the brew head itself, of course. 

Classics purchased before 2018 (or not equipped with the adaptor ring) are not PRO-enabled and cannot support this upgrade/the larger PRO2 parts.