(a) Samples which contain more than 20 pounds shall have not more than one and one half times a specified tolerance of 10 percent or more, and not more than double a specified tolerance of less than 10 percent, except that at least one defective and one off-size onion may be permitted in any sample: Provided, that en-route or at destination when onions in containers of 50 pounds or more are packed to a minimum size of 3 inches or larger not more than three onions or more than 4 percent (whichever is the larger amount) may be affected by decay or wet sunscald: And provided further, that the averages for the entire lot are within the tolerances specified for the grade; and,

(b) Samples which contain 20 pounds or less shall have not more than double the tolerance specified, except that at least one defective and one off-size onion may be permitted in any sample: Provided, that the averages for the entire lot are within the tolerances specified for the grade.