The housing is provided with a slot like {HEAD ~ longitudinal opening} , which on either side is flanked by {TAIL ~ a housing limb}  
is flanked by
The housing is provided with a slot like { HEAD ~ longitudinal opening } , which on either side is flanked by { TAIL ~ a housing limb }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH