Monel fasteners are made from a nickel-copper alloy and exhibit high strength, toughness and good corrosion resistance over a wide temperature range. An outstanding characteristic of Monel fastener is that they offer exceptional resistance to hydrofluoric acid, a particularly tough acid to deal with, in all concentrations up to the boiling point. For hydrofluoric acid applications Monel fasteners are perhaps the most resistant of all commonly used specialty alloys. Monel 400 hex bolts, studs, and fasteners have a hardness of 65 Rockwell B, electrical conductivity at about 3.4 percent IACS, and a specific gravity of 8.83. It is easily fabricated and is strengthened by cold work.