These specifications, including test methods, apply to flexible cellular rubber products known as latex foam rubbers but do not apply to sponge and expanded rubbers. The base material used in their manufacture shall be natural rubber, reclaimed rubber, synthetic rubber, alone or in combination. The structure of latex foam rubbers consists of a network of open or interconnecting cells. Latex foam rubbers are made from rubber latices or liquid rubbers. They are manufactured in sheet, strip, molded, or specific shapes. Latex foam rubbers shall have a vulcanized cellular structure with a porous surface. The cells shall be interconnecting and of a uniform character. Latex foam rubbers shall be either cored or solid. Latex foam rubbers shall have their grade numbers designated by two letters which identify the kind of latex foam rubber as follows: RC for latex foam rubbers cored and RU for latex foam rubbers uncored. Digits following the letters are used to indicate the degree of firmness, the softer grades being identified with the lower numbers and the firmer grades with the higher numbers. These rubbers shall be subjected to the following tests: accelerated aging test, compression set under constant deflection test, flexing test, low temperature test, and static fatigue test.