A threaded fastener has {HEAD ~ a casing} enclosing {TAIL ~ at least three radially inwardly biased arcuate segments} positioned to engage the threads of a bolt or hollow threaded member 
enclosing
A threaded fastener has { HEAD ~ a casing } enclosing { TAIL ~ at least three radially inwardly biased arcuate segments } positioned to engage the threads of a bolt or hollow threaded member
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH