The Equator is an imaginary line that encompasses the Earth. It's location is universally agreed upon despite the fact that it isn't really there. It is represented as 0 degrees, a non space, a point of departure.
Each of the 13 countries that exist along the Equator are represented by a sequence of carefully collected postage stamps. The sequence is cut into two segments along the point at which the Equator divides the country into the North and South Hemispheres.