{HEAD ~ A rotatable fastener} has a head portion with an axially facing ring gear engageable with a complementary gear of {TAIL ~ a drive tool} 
{ HEAD ~ A rotatable fastener } has a head portion with an axially facing ring gear engageable with a complementary gear of { TAIL ~ a drive tool }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL