In direct mail, your mailing piece is your creative asset. There are many different types of mailings in direct mail, and they can be as small or as large as you wish. The size and shape of your mailing piece depend only on your imagination and on the size of your budget for printing and shipping it.
The most common types of mailing pieces are:
Postcards: Can be 3 × 5 inches or larger, with a special offer printed on it.
Flyers: Usually one-page, 8 × 11-inch, folded-without-envelope flyers outlining your business ...