This rounded version slips on to a small rectangular protrusion that comes off of the portafilter body (other versions come with a long square shaft the runs the entire length of the handle), and is held in place by a Allen head screw. There is a half-moon removable insert at the user end of the handle to access the fixing screw (M6 x 12mm hex flange bolt – not included).
Used in some Nuova Baby, Espresso/Dandy and Coffee models, depending on the year of manufacture.