When heated, Thermo-Loc® becomes pliable enough to form around almost any object or material. When it cools, the reusable polymer material becomes rigid, holding your work in place for hand engraving, stone setting, and other detailed operations. To reuse, gently heat the material with a hairdryer, heat gun or microwave oven (without your metal object inside, of course) and form it around another object. Thermo-Loc® is non-toxic and biodegradable and begins to soften around 145°F (63°C). The medium gray color reduces eye strain, making it easier to see your work, especially under bright lights. 1/2 lb package contains approximately 30 Thermo-Loc® Sticks. 6" x 6" non-stick PTFE pad for microwave heating is sold separately.