The adjustable strap 308 in the rear is used to adjust {HEAD ~ the headset} to {TAIL ~ a comfortable tension} setting for many different head sizes 
to
The adjustable strap 308 in the rear is used to adjust { HEAD ~ the headset } to { TAIL ~ a comfortable tension } setting for many different head sizes
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH