In a further arrangement, {HEAD ~ the combined cross sectional area} is {TAIL ~ less than 20%} of the cross sectional area of the hollow interior 
is
In a further arrangement , { HEAD ~ the combined cross sectional area } is { TAIL ~ less than 20 % } of the cross sectional area of the hollow interior
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH