Micro E6B Flight Computer
E6B-1
This pocket-sized, brushed aluminum E6-B is a full-function aviation computer. Popular among military pilots, it features a high-speed and low-speed wind correction slide, high-speed compressibility table, vinyl case, and instruction manual. Micro E6-B performs all the standard manual flight computer functions, and it conveniently fits in a shirt pocket or glove box. 6" x 3-1/2". Made in Korea. NSN 6660-01-171-0181
Check out this short video on calculating time enroute:
For more details, read the Operating Manual.