Show ER-66 megaphone has a built-in siren, maximum 25-watt power requirements, a range of 0.8–2 km, 8 x "C" type batteries, an external power source of a 12V battery or 8 x 1.5V DC, speaker impedance of 8 ohms, dimensions of 230 x 350, and a weight of 1.65 kg.