Knee Map Holder US Navy T93-H-202500 1948
This is an original Knee Map Holder as used by some pilots of the US Navy post WWII.
According to the accompanying bulletin, the board is strapped to the pilots left leg with the map inserted between the plastic panel and the aluminum frame. There is a compass rose mounted to a flexible arm that can be positioned anywhere over the map. A small spring-loaded chain can be extended around the center of the compass to the desired course to determine the correct heading. A Mark 8 flight computer can then be extended from the top to determine the time, distance, and speed information.
A pretty slick little device, but judging from the lack on information on it, it may not have had a lengthy service life. An interesting observation is that the data label is stamped DCNO-AIR in the Distribution field. DCNO-AIR is likely Deputy Chief Naval Operations, Aeronautics.
Measures 8 in x 11 in x 1.5 in. It is in fine condition given its age.