Knife Cabinet with Shadowboard
A "shadowboard" was a peg-board in a locked cabinet used to store large kitchen utensils, such as meat cleavers, knives, and other food preparation utensils. Silhouettes of each knife, tool or implement were painted on the boards. Knives and cleavers were hung over those silhouettes, making it possible for officers to see instantly whether the knife was in its proper place. It was important to keep very close control over such objects, as inmates could use them as weapons.
Golden Gate National Recreation Area