1960s vintage Reading Pacer from the Book-Of-The-Month Club. This is a device to assist with speed reading courses by scrolling a guide bar down the page as you read. It was originally from the Book-Of-The-Month Club and is marked as the BOMC Reading Pacer model 2.
The rate that the guide moves is controlled by the dial and can be set from about 25 words per minute up to 2000 words per minute. The transparent plastic window is about 7.5" x 5".
This has light wear.