{HEAD ~ The firestop} prevents fire and smoke from moving through the inner passageways of the pipes of a drainage system by blocking the inner passageway of {TAIL ~ the pipes} with a fire resistant plug  
{ HEAD ~ The firestop } prevents fire and smoke from moving through the inner passageways of the pipes of a drainage system by blocking the inner passageway of { TAIL ~ the pipes } with a fire resistant plug
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH