Expobar or E61 Grouphead Flow Restrictor code 50020000 should be compatible with most E61 standard groupheads.
This is used as the name mentions, to restrict the flow of water that reaches the GH.
Could be useful to mantain a lower temperature of the grouphead or to just have lower water output in your machine.
Expobar or E61 Grouphead Flow Restrictor code 50020000 does not and should not affect the pump (vibe or rota) – if it does not have a factory working problem.
Can be installed in the IN pipe, BEFORE the GH.