When {HEAD ~ casing 301 a} and 302 a are installed into {TAIL ~ said mounting brackets}, the optics within said casings can be automatically returned to a position that does not require realignment 
When { HEAD ~ casing 301 a } and 302 a are installed into { TAIL ~ said mounting brackets } , the optics within said casings can be automatically returned to a position that does not require realignment
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH