A (size)
The largest standard cigar size is an "A" which is also known as a gran corona (see photo). The standard for an "A" is 9 1/4 inches long by 47 ring gauge, but some non-Cuban "As" have slightly different dimensions. The most famous example is the Montecristo "A" from Cuba. All "As" take a very long time to smoke, perhaps as much as two hours.