Got this about a month ago from Siegel. This is my favorite of all the stamps I own right now.
I am curious as to why the premium on the C6 block compared to C1-C5? The production numbers aren't that different? Is it just desirability? Was it actually in use more? I read the literature on stampsmarter about all the these early airmail stamps but didn't come across much as to why it would be such a higher premium.
Quick C6 Summary: The DeHavilland Biplane is pictured on this 24¢ airmail issue. This aircraft eventually replaced the Jenny in carrying the mail. This particular stamp was issued to provide payment for night flights from New York all the way to the Pacific Coast.
Quantities Issued(From scott)