a movable cover member rotatably mounted to said side walls, said {TAIL ~ cover member movable} between {HEAD ~ a first position} engaging said front wall portion and a second position adjacent said rear wall portion 
a movable cover member rotatably mounted to said side walls , said { TAIL ~ cover member movable } between { HEAD ~ a first position } engaging said front wall portion and a second position adjacent said rear wall portion
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH