About this item Weatherproof and rugged construction. High SPL, crisp penetrating sound. Voice coils precision-wound on an aluminium bobbin for efficient heat dissipation. AU-40XT has a built-in 100V transformer with easily selectable power taps/impedance by changing the position of the rotary switch at the rear. Degree of protection IP 66 provided, when mounted on a reflex horn, against foreign particles such as dust and jets of water thus making them ideal for outdoor use. Meets EN 60529.