34 x 27 x 2 mm. This is for the exchangers on the NS Lever group, the NS-85 Manual group and the NS-85 16/M (pre-2000) Solenoid groups, NOT for the Europa-95, Golden Coffee or Sprint models. NS-85 16/M models manufactured after (approximately) the year 2000 use the same gasket as the Europa-95 and Sprint models, which is referred to as the "1/2" version, part SM_364.
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.