The Shure Model SM81 is a high-quality, unidirectional condenser microphone designed for studio recording, broadcasting, and sound reinforcement. Its wide frequency response, low noise characteristics, and low RF susceptibility have made it a standard for applications involving acoustic instruments, especially guitar, piano, and cymbals. The SM81 is ruggedly constructed. It operates on phantom power and performs over a wide range of temperatures and humidity conditions. It is furnished with a swivel adapter, attenuator-switch lock, foam windscreen, and case for carrying and storage. Features: 20 Hz to 20 kHz frequency response. Flat response curve for accurate reproduction of sound sources. Low noise and high output clipping level. Low distortion over a wide range of load impedances. Cardioid polar pattern, uniform with frequency and symmetric about axis, providing maximum rejection and minimum coloration of off-axis sounds. Low RF susceptibility. Selectable low-frequency response: flat, 6 or 18 dB/octave rolloff. 0 dB/10 dB lockable attenuator switch. Phantom powering (DIN 45 596 voltages of 12 to 48 Vdc). Rugged steel construction for durability. Field-usable over wide range of temperature and humidity conditions.