The Red Armor (or RA) is an Armor in Quake. It absorbs 80% of damage and gives somebody 200 Armor points, making it extremely effective against every Weapon and Enemy in the game. When you have it, do not replace it with another Armor when it gets low! Its absorption rate means that it'll protect one well until all of one’s armor points are gone.
Players in Red Armor can only collect Yellow Armor when their Armor points are below 113, and Green Armor when they are below 38.
In MP, the Red Armor is devastating. Its absorption rate means that a player that has it can brush off even a direct hit with a rocket multiple times. A player that has it and a 100 Health is almost invincible. Since there's no way to tell if an enemy has Red Armor, you'll have to be ready for an extended firefight with somebody that has it.
A room that has Red Armor is usually a major control point in a map, given how powerful it is. As soon as a match starts, some players tend to rush the RA room so that they can grab it. If you get in control of it, DO NOT let go of it! If you control the RA room as long as possible, you'll get a lot of frags and be able to deny enemies from using it. If you do lose control of it, try to get back in ASAP and regain control while the others are fighting to see who will control the RA room.