GRS Thermo-Loc handles feel like wood, but are virtually unbreakable- they can even take the force of a hammer without splitting. The best feature is how they hold gravers, files and tools. Inside each handle is a formed piece of GRS Thermo-Loc that softens with heat. As soon as the Thermo-Loc core is softened, insert the tool and move it to the desired position. When the Thermo-Loc core returns to room temperature, the tool is secure and ready for use. Set includes four Thermo-Loc core handles, one of each color: Rosewood, Honey Beige, Pewter and Dusk.