{HEAD ~ a counter tool} placed in opposition to the sonotrode to define a gap there between for passage of {TAIL ~ the material web} 
{ HEAD ~ a counter tool } placed in opposition to the sonotrode to define a gap there between for passage of { TAIL ~ the material web }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL