Tamper-proof fastener

Claim 1

A TAMPER-PROOF FASTENER, COMPRISING; A MEMBER HAVING AN OUTER CYLINDRICAL SURFACE PROVIDED NEAR ONE END THEREOF AND INCLUDING AN ANNULAR SHOULDER PROVIDED THEREON AND MEANS FOR FORMING A SECOND ANNULAR SHOULDER IN SPACED RELATION THERETO, A HEXAGONAL SURFACED COLLAR MEMBER INCLUDING A BORE RECEPTIVE OF THE SURFACED END OF SAID MEMBER THEREWITHIN AND FOR ROTATABLE ENGAGEMENT AND POSITIVE LOCATION ON SAID MEMBER BETWEEN SAID SHOULDERS, A KEY SLOT COOPERATIVELY FORMED IN THE RESPECTIVELY ADJACENT SURFACES OF SAID SURFACED END AND SAID COLLAR MEMBER AND EXTENDING THROUGH SAID SHOULDERS AND BEING OPEN AT BOTH THE TOP AND UNDERSIDE THEREOF, SAID KEY SLOT BEING ALIGNED WITH A CORNER OF THE HEXAGON OF SAID COLLAR MEMBER AND INCLUDING AN ABUTMENT SHOULDER EXTENDING TRANSVERSELY OF THE BORE IN SAID COLLAR MEMBER, THE KEY SOLT IN SAID SURFACED END INCLUDING AN OPPOSED ABUTMENT SHOULDER EXTENDING TRANSVERSELY OF THE AXIS THEREOF, A SHEAR RESISTANT KEY REMOVABLY RECEPTIVE IN SAID KEY SLOT BETWEEN SAID ABUTMENT SHOULDERS FOR LOCKING SAID MEMBERS AGAINST RELATIVE ROTATION THEREBETWEEN, AND SAID KEY HAVING AN END THEREOF ANGULARLY DISPOSED APART FROM THE REST THEREOF AND RADIALLY INWARDLY OF SAID COLLAR.