US Patent 10221946 Security fastener

A fastener having a head is provided. The fastener includes a unidirectional inner drive including an inner lobe having an inner ramp surface adjacent to an inner drive abutment surface adapted to receive a torque to effect a clockwise rotation of the fastener. The fastener further includes a concentric unidirectional outer drive including an outer lobe having an outer ramp surface adjacent to an outer drive abutment surface adapted to receive an inverse torque to effect a counter-clockwise rotation of the fastener.