Super Armor is a pickup that gives the player 200 armor points when picked up. However, it will not go beyond the 200 armor points limit.
Its appearance varies on the game; in SS1, SSHD and NE, Super Armor is a huge red armor, while in SS2, it is a full set of armor that has a chest piece, helmet, shield and legs. In SS3:BFE Fusion, Super Armor can only be found on the final level, The Guardian of Time.
If Super Armor appears normally, it is a big sign that the player is going to be in a very large and dangerous fight soon, and should prepare accordingly.
Super Armor can also be found in secrets, and in that case, is never a sign that the player will be involved in a huge battle soon. Most of these are well hidden or difficult to get, as they are very useful.