The metal cover may provide {HEAD ~ a plurality} of {TAIL ~ legs} and fins each coming in contact with and pushing the walls of the groove 
of
The metal cover may provide { HEAD ~ a plurality } of { TAIL ~ legs } and fins each coming in contact with and pushing the walls of the groove
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH