In {TAIL ~ the rotary version}, the vent follower operates in {HEAD ~ a wiper type fashion} 
In { TAIL ~ the rotary version } , the vent follower operates in { HEAD ~ a wiper type fashion }
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD