E‑ZPass tags are active RFID transponders, made exclusively by Kapsch TrafficCom (formerly Mark IV Industries Corp—IVHS Division). They communicate with reader equipment built into lane-based or open-road toll collection lanes by transmitting a unique radio signature. The most common type of tag is an "internal tag" that can be mounted on the inside of the vehicle's windshield in proximity to the rear-view mirror. Though toll agencies advise adherence to the windshield with mounting strips (usually 3M's Scotch brand "Dual Lock" fasteners), third-party options using trays with suction cups to adhere a pass to a windshield temporarily if used in multiple vehicles are available. Some vehicles have windshields that block RF signals; for those vehicles, historical vehicles, and customers who have aesthetic concerns, an "external tag" is offered, typically designed to attach to the vehicle's front license plate mounting points.