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