Abstract: An ultrasonic and electrosurgical handpiece housing has an axis, a distal end, a proximal end and a passage defined by an inside wall. A piezo stack has elements carried along a plane generally transverse to the axis. A retainer for the elements has distal, intermediate and proximal portions. The distal portion has a fastener; the proximal portion has a threaded shoulder bolt. The stack about the shoulder has an energy input and a reference output positioned axially apart from one another. An insulating sleeve about the bolt is between central openings of the elements and the bolt. A pair of insulators about the bolt has the stack therebetween; one insulator is between the plane and the stack and the other is near the threads. The intermediate portion attaches to the housing at the plane with decoupling and sealing. An irrigation channel conveys fluid. The drive energy input, the feedback signal and the reference outputs are insulated by the sleeve and pair from the bolt.