Hoyt Electrical Instrument Works Vintage Audio AL20SQ Series Volume meter (VU meter)

"This square vintage style meter is constructed with gloss black phenolic plastic and a glass window . Suitable for rear panel clamp mounting with internal or external illumination options. Hoyt is an authorized distributor for Sifam VU in the United States.","Key Base Specifications and Features (Consult Datasheet or Factory for Complete Details)","Accuracy: A low range ac voltmeter offering a performance close to that of a full specification vu meter. Suitable for connecting across a 600 ohm line and self-contained except for requiring an external 3k6 resistor. Calibrated for use with a 3k6 ohm resistor 4vu above the scale marking so that the reference deflection (0vu) is produced by a signal 4vu above 1mW in 600ohms (1.228V). A variation in over swing between 0 and 5% can occur since the damping is not individually adjusted on each AL meter but allowed to fall within normal process parameters.","Operating Temperature: -13°F to 131°F (-25°C to 55°C)","Performance: IEC 268-17"