The housing is further formed with {HEAD ~ a cylindrical cavity}, and a manually rotatable hollow cylinder is received within {TAIL ~ the cylindrical cavity} 
The housing is further formed with { HEAD ~ a cylindrical cavity } , and a manually rotatable hollow cylinder is received within { TAIL ~ the cylindrical cavity }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL