A fine 25c airmail cover to Pakistan, sent August 1956 and franked with a single 25c Chemical industry. Karachi receiving backstamp.
Unusual because:
Pakistan is an unusual destination and the 25c airmail rate is much less common than the 15c rate to Europe.
Our estimate of the value of this cover based on the above factors is $20. To understand how we have assessed the cover and arrived at this estimate and to gain a broader understanding of postal history collecting, I would suggest you read the article linked here. It should clarify the factors that make covers, and this one in particular scarce, and will help you to understand why we have estimated it at this amount.
