The Victoreen Instrument Co. CDV-727 Model 1

Radiological Survey Meter
The CDV-727 measures gamma radiation from 0 - 100 roentgens per hour.
It uses a hermetically sealed ion chamber.
Uses 2 "D" size 1 1/2 volt batteries.
Dimensions: 8 1/2" x 4 1/2" x 6"