Text on case reads:

U.S.

Applied Devices Corp

Contract No. DAAK01-67-C-D484

Accessory Case

For

Model 99

Surveying Instrument, Distance Measuring

Electronic Microwave Miniaturized,

Dual Purpose Unit.

200 Meters To 50 Kilometers

12 To 24 VDC and 115V, 60HZ, 1ø AC

With

Radio Telephone Headset

And Accesories

https://www.bunkerofdoom.com/mil/model99/index.html

From the above link, where a near-identical model was found;

The model 99 surveyng instrument is a CW microwave tranceiver operating between 10.1 and 10.3 GHz with 30mW power. Two of these are set up and aimed at each other and the distance is indicated on an electromechanical digital readout. Not only does it measure distance from 200M to 50KM with an acuracy of a couple of cM, it also provides voice communication between the two units. It is of great interest as well to Amateur radio operators since it operated in the 10.0GHz to 10.5GHz band and is basically a "ready to use microwave communications set in a box". RF power is provided by a Varial VA-203K tunable klysron. All internal DC voltages are derived from an internal switching power supply that operates from batteries or an external 12 or 24 volts DC supply. The highest internal voltage is 300VDC, the lowest, 5VDC. An optional 115VAC supply can be used to provide DC power for the unit.

Besides the unit shown open for inspection in the lab, there are six more of them in the crates, a total of seven instruments. It takes two to do a measurement or set up a voice link.

There is also a similar instrument, perhaps compatible (same contract?), described as "X BAND RANGING Freq. Band: 10.1-10.3 GHz. Pwr. Output: .03 Watts. Range: 200 meters-50 Km. Indicator: Dial Type. Klystron Type: VA-203K. Rep rate: CW. Antenna: 12" dish. Pwr input: 12 VDC, 115V, 60 Hz. Mfr: Fairchild MC-8.", advertsied by Radio Research Instrument Co.. That seems very much like the model 99 here.

Full kit in above link is not included; only the communication module pictured is included.