(a) Head lettuce, which is packed or placed in layers in any container, shall not vary in size in any one container more than 15 percent of heads which would fairly tightly pack a size, larger or smaller, than the size which is marked. It shall be fairly tightly packed with the same numerical count of regularly arranged heads in each layer. None of the heads shall be placed outside of the regular arrangement of two uniform flat layers in standard container numbers 45A, 45B, 45C, or 45F. If, however, 2 ½ dozen heads of lettuce of the 2 ½ dozen size when fairly tightly packed in standard container numbers 45A, 45B, or 45F are packed in such containers, six heads of the same size or dimensions as the heads which are contained in the upper and lower layers may be placed between such layers if the upper and lower layers consist of 12 heads each and the total count in the container is 30 heads.

(b) Not more than 15 percent, by count, of the individual heads of partially or completely cored lettuce in any master container may measure more than 1 ½ inches larger in diameter than the smallest head in the container.