CMP460 speaker microphone meets the ANSI/UL 913-6th Ed. Requirements for: Class 1: Flammable Gases, Vapors, or Liquids Div. 1 Group A (Acetylene) Group B (Hydrogen) Group C (Ethylene) Group D (Propane) Class 2: Combustible Dusts Div. 1 Group E (Metals) Group F (Coal) Group G (Grain) Class3: Ignitable Fibers and flyings.