{HEAD ~ Each flap} can be pulled back from {TAIL ~ the base member} and then can be resecured once an instrument has been inserted between the flap and the base member 
pulled back from
{ HEAD ~ Each flap } can be pulled back from { TAIL ~ the base member } and then can be resecured once an instrument has been inserted between the flap and the base member
HEAD HEAD HEAD HEAD HEAD HEAD 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