Chamois packaged or labeled for retail sale is exempt from the requirements of § 500.13 of this chapter which specifies how measurement of commodities by area measure should be expressed: Provided:

(a) The quantity of contents for full skins is expressed in terms of square feet with any remainder in terms of the common or decimal fraction of the square foot.

(b) The quantity of contents for cut skins of any configuration is expressed in terms of square inches and fractions thereof. Where the area of a cut skin is at least one square foot or more, the statement of square inches shall be followed in parentheses by a declaration in square feet with any remainder in terms of square inches or common or decimal fractions of the square foot.