{HEAD ~ A wood based material} may be formed having a permeability which is {TAIL ~ at least 5 times that} of the untreated wood 
{ HEAD ~ A wood based material } may be formed having a permeability which is { TAIL ~ at least 5 times that } of the untreated wood
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH