Staggered pins are in different slots at various distances from your eyes. They are usually stacked behind one another thus giving you the illusion that the pins are right next to each other (when shooting) but in reality the pins are right behind or in front of each other. When your sight pins are lined up slightly to the left or right of your line of sight then the pins do not appear to be in the same line vertically but rather "staggered". One pin looks further in or out than the others. Several sights over the last 5 or 6 years have used multiple slots, angled pins or curved pin designs to get all of the pin heads into the same plane. This eliminates the "staggered pin" visual illusion.