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