A surgical instrument, comprising: a handle assembly including a connector for electrically coupling the handle assembly to a source of electrosurgical energy; an end effector including a pair of opposed jaw members operatively coupled to a distal end of the handle assembly such that at least one of the jaw members is induced to move relative to the other jaw member between open and closed positions in response to manipulation of the handle assembly; a base supported on at least one of the jaw members, the base including a mechanical mating feature (108,110) and an electrically conductive region thereon, the electrically conductive region in electrical communication with the connector; and a selectively removable seal plate supported on the base, the seal plate including a mechanical mating feature (112,114) complementarily engaging the mechanical mating feature of the base to maintain the seal plate in position on the base during use, and an electrically conductive region positioned to contact the electrically conductive region of the base when the mechanical mating features of the base and seal plate are engaged, the electrically conductive region in electrical communication with an electrode on the seal plate; wherein the complimentarily-engaging mechanical mating features includes a pair of spaced protrusions (108,110) on one of the base and the seal plate, and a pair of spaced recesses (112,114) open to opposing sides of the other of the base and the seal plate such that the seal plate may be twisted onto the base, characterised in that the protrusions are posts, are spaced in a generally longitudinal direction and extend from the base, and wherein the recesses are open to opposing lateral sides of the seal plate. a handle assembly including a connector for electrically coupling the handle assembly to a source of electrosurgical energy; an end effector including a pair of opposed jaw members operatively coupled to a distal end of the handle assembly such that at least one of the jaw members is induced to move relative to the other jaw member between open and closed positions in response to manipulation of the handle assembly; a base supported on at least one of the jaw members, the base including a mechanical mating feature (108,110) and an electrically conductive region thereon, the electrically conductive region in electrical communication with the connector; and a selectively removable seal plate supported on the base, the seal plate including a mechanical mating feature (112,114) complementarily engaging the mechanical mating feature of the base to maintain the seal plate in position on the base during use, and an electrically conductive region positioned to contact the electrically conductive region of the base when the mechanical mating features of the base and seal plate are engaged, the electrically conductive region in electrical communication with an electrode on the seal plate; wherein the complimentarily-engaging mechanical mating features includes a pair of spaced protrusions (108,110) on one of the base and the seal plate, and a pair of spaced recesses (112,114) open to opposing sides of the other of the base and the seal plate such that the seal plate may be twisted onto the base,