The grey ceramic cover features flecks to imitate real spa-stone coloring. Drop a few of drops of essential oil on refillable oil pad, then re-assemble warmer. Gently warms oil to release the fragrance from oils for aromatherapy. Perfect for smaller spaces or bathrooms. luggables can be used in both vertical and horizontal outlets by twisting the plug base, making them ideal for above counter outlets in small rooms and spaces. Fits Standard US 3 prong outlets.