1 mm "fine thread". Old, larger diameter knob for the Faema Express, Special and No Stop models. Also fits the Victoria Arduino Athena Leva model.
1 mm thread pitch means that these have threads on the inside that measure 1 millimeter from thread peak to thread peak, referred to as "fine" thread. These work with any valve that uses the F_475 valve fitting.
These look very similar to the La Marzocco MZ_11 knob, but the Marzocco use a 2 mm thread version.
WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.