Insert in place of your old Bendix/King KT-76 or KT-78.

ALL NEW AT165K.  Exciting features such as our one-
touch code entry knob, multiple timers with alarm output, and
altitude display with visual and audible altitude hold warning
make the AT165 the pilot’s choice for the modern avionics
panel. Our innovative dual independent displays with single
button data exchange will always give the pilot the ability to fly
confidently in the unlikely event of a display problem.
The AT165 is both a receiver and a 250W transmitter which
responds automatically to ground based radar interrogation.
When interrogated, the squawk code and the pressure altitude
of the aircraft are displayed on the ATC radar screen. Audible
alerts from the AT165 warn the pilot when flying outside of
the desired altitude range.