This is an brass valve with square fitting and threaded base. It fits on the lower spring inside the piston under the group - see blue arrow. The rubber basket eventually goes hard and shrinks and the brass wears over time. (We also have the triangular version with threaded base 27.3mm)
Specifications:
Length:27.6mm
Type: Square tip with 3mm threaded base
Material: brass CW510L (OT57) low lead content
Fits most models including :
BEZZERA: GALATEA, GALATEA DOMUS, GIULIA, UNICA
BFC: Royal
BRASILIA: CENTURY, DE-CURTIS, GRADISCA, MINICLASSIC, PORTOFINO
CIME: CO.01, CO.06, CO.11
ECM :CLASSIKA II, MECHANIKA, SYNCHRONIKA, TECHNIKA III