Usually {HEAD ~ the lateral dimensions} of {TAIL ~ the fibers} range from 20 μm to 125 μm 
of
Usually { HEAD ~ the lateral dimensions } of { TAIL ~ the fibers } range from 20 μm to 125 μm
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH