Aquatic Technology 7028WS1818E 18"x18" Red Turn On The Before Entering Sign measures 18 x 18 inches, is printed on .040 mil Styrene Plastic with 4 inch lettering and is designed to prevent personnel from entering chemical room before turning fan on. Our general safety signs used to indicate general instructions relative to safe work practices and reminders of proper safety procedures. This sign is lightweight, durable, and waterproof for indoor or outdoor use.