ATP35 - 

The ATP-Series of attenuators allows the output level of a network of 25 V or 70 V speakers to be controlled from a wall-mounted volume control, without affecting overall amplifier volume settings. A bypass function overrides the volume control knob setting when activated by 9V to 30V DC. Applying 9 V to 30 V DC between pins labeled D+ and D- bypasses the volume control function and provides full volume audio to the speakers. The ATP-Series attenuators feature etched faceplate markings.
Features

Adjusts loudspeaker output levels on 25 V and 70 V systems

Bypass function allows important and emergency announcements to be heard at the highest level even if local attenuator volume is set low or off

10 attenuation steps and an off setting

Attenuation in 3 dB increments except for two lowest settings, which provide 6 dB reduction increments

Mounts in standard electrical box, double (ATP35)

Convenient pluggable screw terminal connections

Speaker Types: 25 V and 70 V

Bypass Control: 9 V –30 V DC @ 22 mA max.

Power Rating: 35 Watts

Gang Box: Dual

Dimensions: 43⁄4"(W) × 43⁄4"(H) × 3"(D)

Shipping Weight: 2 Lbs.