E61 group

Image of the E61 group

This is what an E61 group looks like, when you read the term "e61 HX machine" or "e61 group". It's extemely heavy chromed brass, weighing at least 8lbs, that is considered the standard for espresso machine groups. It's portafilter is a standard 58mm and parts are readily obtainable. It has been in use since the 60s and is still considered one of the best groups, to have good thermal stability and produce excellent espresso shots.