Fastener having concave locking fins

Claim 1

A ONE-PIECE BOLT FOR CONNECTING A PAIR OF HOST MEMBERS HAVING HOLES FOR RECEIVING THE BOLT, SAID BOLT HAVING A SHANK WHICH IS TO BE RECEIVED IN THE HOLES, A THREADED PORTION DISPOSED AT THE FORWARD END OF SAID SHANK TO EXTEND OUTWARDLY OF THE HOLES IN SAID HOST MEMBERS, TO RECEIVE A NUT TO APPLY CLAMPING PRESSURE TO SAID HOST MEMBERS, AN ENLARGED HEAD AT THE END OF SAID SHANK REMOTE FROM SAID THREADED PORTION HAVING A BEARING SURFACE FOR ENGAGING THE ADJACENT HOST MEMBER, SAID BEARING SURFACE TAPERING INWARDLY TOWARD SAID SHANK AT AN ACUTE ANGLE THEREWITH TO DEFINE A CONCAVE SUFFACE, SAID HEAD BEING COMPRISED OF ALTERNATE CONVEX AND FLAT SURFACES WHEN VIEWED FROM ABOVE SAID HEAD, SAID HEAD HAVING A PERIPHERAL CONFIGURATION OF ALTERNATELY SPACED CONVEX AND CONCAVE ARCS WHEN VIEWED FROM THE BEARING SURFACE AND A RADIALLY INWARDLY CONCAVE FIN EXTENDING ALONG EACH OF THE CONCAVE ARCS AND PROJECTING AXIALLY BENEATH THE BEARING SURFACE THEREOF AND BEING DIRECTED SLIGHTLY INWARDLY TOWARD SAID SHANK, SAID FINS EMBEDDING IN THE ADJACENT HOST MEMBER TO PROVIDE A LOCKING ENGAGEMENT THEREWITH WHEN SAID HEAD AND NUT ARE IN CLAMPING ENGAGEMENT WITH SAID HOST MEMBERS.