The Mark I was the first Iron Man armor. Stark had only a few days to build it with few resources. In addition, he didn't have the assistance of J.A.R.V.I.S. his A.I. And so the final product came out crude and bulky. It had very limited articulation. It magnified his strength greatly. It could only protect Stark from small arms of fire and extreme g-forces. It also featured a rocket which he used to seemingly kill Raza. It sports twin flame throwers, one on each arm. He used it to kill many ten rings soldiers and burned their stockpile of his weapons. Lastly it features thrusters on each boot for short jumps.