Question

What is a card which is approximately size of the postage stamp

Answer 1

Explanation:

To be eligible for mailing at the price for “letters,” a piece must be: Rectangular. At least 3-1/2 inches high x 5 inches long x 0.007 inch thick. No more than 6-1/8 inches high x 11-1/2 inches long x 1/4 inch thick.