|Lacquered, Tarnish-Resistant Wire- Half hard wire thats ideal for jewelry making, wire wrapping, crafting, scrapbooking, and much more! - 99.99% Copper core - Available in 16-28 gauge - Lead Free, Nickel Free. Medium temper wire is flexible and well-suited for creating components with sharp angles or that need to maintain their shape under moderate stress, such as ear wires, jump rings, or weight-bearing parts of wire-wrapped jewelry. When used to create an element like a clasp, which will be subjected to high stress, it should be hardened after shaping. This can be done by placing it on an anvil or bench block and striking it with a nylon-jaw hammer. "