O.E.M. CMA product, stamped "WEGA 12227". This is the same as the F_59, but is made with a softer rubber. 73 x 57 x 8 mm will fit any E61 style group: Astra, BFC, some models of Brasilia, ECM, Faema, Fiorenzato, Futurmat, Grimac, Isomac, Orchestrale, Royal, Sanremo and Wega. Also available in 8.5 and 9mm versions.
If your portafilters are worn, they may be engaging too far to the right (and if you don't want to buy new portafilters), you may want to consider purchasing one of the thicker gaskets.
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.