Electrosurgical unit (10) includes a shell (20), and an axis (50) is connected to shell and the distal end of axis is arranged in end effector assembly (100). Actuator assembly (100) includes the first and second jaw members (110,120), it is therein at least one can be from first position, wherein it is close to each other to be disposed relative to the mutual at least second position in spaced relation for jaw member, and wherein jaw member cooperation is with grasp tissue therebetween. Second claw component (120) includes that conductive tissue surface (129) and protrude element (122) extend therefrom. Prominent element (122) are configured as extending one section of second jaw member along elongate strip. Electrosurgical unit (10) also includes that vibration coupling device (60) and an oscillation mechanism (30) are configured to generate the vibration coupling device (60) of mechanical oscillation. Vibration coupling device (60) includes proximally and distally being removably couplable to the second first jaw member (120).
