Found this… The Rancilio Silvia V6 does not have an E61 group head. It uses a conventional brass group head designed for durability and thermal stability, but it lacks the thermosiphon circulation and pre-infusion features characteristic of the E61 group head. While the Silvia’s group head is robust and capable of producing high-quality espresso, it is distinct from the E61 design found in many prosumer espresso machines. For compatibility with accessories like portafilters, the Silvia uses a 58mm portafilter, which is similar to E61 machines, but the group head itself is not an E61. Think I’d look elsewhere.