Empire Flexible Silicone Skin Case for ZTE Groove X501 - Black Specially designed Flexible Silicone Skin Black Case for ZTE Groove X501. Made from fully treated silicone. No mixes or blends. Chemically stable, even when impacted by heat or environmental impact. Insoluble in water, corrosion resistant, a virulent insipidity. EMPIRE is a registered trademark with the USPTO.