Tamper-proof 6-Lobe 6-Lobe Slotted Indented Hex washer Tamper-proof Hex Socket Hex Socket Indented Hex washer Tri-Wing Type 2  (Frearson) Phillips Pyramid Head One-Way Phillips Combo Phillips Pyramid Head Spanner Combo Phillips Conventional Pyramid head Clutch Square Drive Square/Slot Combo Holt Type 1A  (Pozi-Drive) Cross-slot Tamper-proof Pyramid Head Hex Head