Vintage Metal Light Box - Military / Government Visual Acuity Testing Device

Description

Vintage Metal Light Box - Military / Government Visual Acuity Testing Device
This is a gray metal box that is 6.25" long x 4" tall x 4" wide.  It has a handle on the back to pick it up when it is hot.  It has a glass slide that can be moved in 4 positions.  It has a heavy duty power cord with a rocker switch.  Inside is an incandescent bulb.  It does not project on a wall but lights up the symbol brightly to measure visual acuity in an eye test.