Loop Powered Open Category Detector Base Sounder Strobe available in isolated/ non isolated version. Requires a B501AP base for fast and simple installation for Morley detectors. The Morley-IAS IAV sounders are designed to inform building users of an emergency. The IAV range of intelligent addressable, loop powered, audio-visual sounders include a comprehensive selection of elements designed to meet the majority of fire alarm installation requirements. The sounders use the Morley-IAS Digital Protocol to minimize power consumption and allow longer loop lengths.