A Class is an archetype of Level 4 or lower monsters of various Attributes and Types, mostly Warriors and Machines. They represent military based objects and stuff. The archetype is called a "pseudo-Union" one. Even though the archetype has a lot of characteristics that Union Monsters possess, they are not Union Monsters because they lack the "one at a time" condition, allowing an "A Class" to be equipped with 2 or more such monsters, while they have the flexibility of them being unequipped to Special Summon them, or protect them from destruction, assets still taken from the Union Monsters. The archetype's members are 26, which is equal to the number of letters of the English alphabet. This is because the first name of each of the A Series monsters starts with a different letter, which is a reason it is the alter ego of the AlphaMechs.