In order to allow for variations incident to proper grading and handling in each of the foregoing grades the following tolerances, by weight, are provided as specified:

(a) For defects:

(1) U.S. No. 1 and U.S. No. 2 grades. Not more than 10 percent of the onions in a lot may fail to meet the requirements of these grades, but not more than one-fifth of this tolerance, or 2 percent, may be allowed for onions which are affected by decay or wet sunscald.

(2) U.S. Combination grade. When applying the foregoing tolerances to this grade no part of any tolerance shall be allowed to reduce, for the lot as a whole, the 50 percent of onions of the U.S. No. 1 grade, but individual containers shall have not less than 40 percent of the U.S. No. 1 grade.

(b) For size:

(1) Not more than 5 percent of the onions in a lot may be smaller than the minimum diameter specified. In addition, not more than 10 percent of the onions in a lot may be larger than the maximum diameter specified.

(2) When a percentage of the onions is specified to be a certain size and larger, individual packages containing more than 10 pounds may have not less than one-half of the percentage specified: Provided, that the entire lot averages within the percentage specified.