Here, {TAIL ~ brush member 4 a} is spaced apart from {HEAD ~ brush member} 4 b 
Here , { TAIL ~ brush member 4 a } is spaced apart from { HEAD ~ brush member } 4 b
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH