PID KIT for Gaggia Classic Pro & Classic & Home w/ pre-infusion
[KIT-GGP]

I've been using this for a year now -- perfect and consistent shots, and amazing microfoam for my morning cappuccino. I've now ordered two more -- one for each of my sons.
When I wired mine I screwed up one connection, shorted out the unit and received amazingly considerate support.
I've seen reviews that suggest the pre-infusion isn't worth it -- I find it valuable for the automatic timing, as well as for the pre-infusion itself.