Air Force because they are the most important in a battle. Fighters for their speed, helicopters for their versatility. Calvendo calendars are premium products - a bit more pricey than others but with added benefits: Our calendars always look beautiful on your wall because we produce them locally with premium paper and sophisticated spiral binding, ensuring easy turning of pages and flat hanging against the wall. A protective transparent plastic cover sheet provides added stability. Treat yourself to a Calvendo calendar and you get something that looks better all year round.