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