Tubular pin tumbler lock - Design. 1  The design of a tubular lock is similar to the pin tumbler lock, in that there are several stacks of pins. The key is a cylinder shape with notches cut around the outer or (rarely) inner edge. Each of these notches depresses a single pin inside the lock to a specific height allowing the lock cylinder to turn freely.
With more than 31,000 retail locations and the most frequently visited website in the federal government, usps.com, the Postal Service has annual revenue of more than $65 billion and delivers nearly 40 percent of the world's mail.
Full Answer. The USPS dictates size standards for mail in the United States based on the requirements of its automatic mail-sorting equipment. The minimum postcard size is 3.5 inches by 5 inches. The maximum postcard size is 4.25 inches by 6 inches. The USPS also requires the postcard be between 0.007 inch and 0.016 inch thick.