<p> Minimum Size: Pieces that do not meet the following
requirements are prohibited from the mails:
<list style=hang>
<item>a. All pieces must be at least .007 inch thick, and
<item>b. All pieces (except keys & identification devices) that are 1/4" or less in thickness must be:
<list style=hang>
<item> 1. Rectangular in shape,
<item> 2. At least 3 1/2" high, and
<item> 3. At least 5" long.
</list>
Note: Pieces greater than 1/4" thick can be mailed even if they measure less than 3 1/2" x 5".
</list>
</p>
<p>Nonstandard Mail: First-Class Mail, except Presort First-Class and carrier route First-Class, weighing one ounce or less, and all sigle-piece rate third-class mail weighing one ounce or less is nonstandard (and subject to a $0.10 surcharge in addition to the applicable postage and fees) if:
</p>
<list style=hang>
<item> 1. Any of the following dimensions are exceeded: Length-11 1/2", Height-6 1/8", Thickness-1/4", or
<item> 2. The length divided by the height is not between 1.3 and 2.5 inclusive.
</list>
<p> The nonstandard surcharge for Presort First-Class and carrier route First-Class is $0.05.
</p>
<p>Source: United States Postal Service; Notice 59, Jan. 1991.
