The precise density times thickness gage (DXT) was developed at Los Alamos Scientific Laboratory during 1951. The gage measures the transmission of gamma rays from cobalt-60 through materials under examination; because of the nature of the absorption of high energy radiation, the variations in transmission can be evaluated to give precise information about the uniformity of the materials in terms of the product of density and thickness. If one of these quantities can be held constant or evaluated by another method, the gage measurements will evaluate the other quantity.