New, sealed Apple version 3 ROM high for the Macintosh Plus. This is one of two 128K ROM chips on the Macintosh Plus logic board. There were three versions of this ROM identified by the last character of the Apple part number on the chip i.e. 342-0341-A, 342-0341-B or 342-0341-C.
NOTE : This v3 ROM high must only be used alongside the v2 ROM low (342-0342-B).