Cleaning out barn.  In box.  Not used in 40+ years.  Don't know how to test.  Appears to have everything including manual.

AI stuff:
The Vintage Sears Craftsman Inductive Timing Light, model 28 2134, is a diagnostic service tool designed for automotive use. Made in the United States, this timing light utilizes inductive technology to accurately determine engine timing. The brand, Sears Craftsman, is known for its quality and durability in the automotive tools and supplies industry, making this timing light a reliable option for mechanics and car enthusiasts looking to accurately diagnose and adjust engine timing.