Shure SM81 Cardioid Condenser Microphone The Shure SM81 Condenser Mic is a unidirectional cardioid mic with studio, broadcast, and sound reinforcement versatility. Its wide frequency response, low noise, low RF susceptibility, and rugged construction allow it to excel in all applications. It is furnished with a swivel adapter, 10dB attenuator with locking switch, a 3-position low-cut filter, foam windscreen, and a case for carrying and storage.