The Sub-Zero Battlesuit is a suit of armor that Edd made in "The Eds are Coming." The purpose of the armor was to deflect the heat vision that Edd believed the "aliens" possessed. To this end, the suit was constructed from several bags of frozen food and some bags of ice. These were held together by tape. Although the battlesuit may have worked, it was quite small, and could only cover the shoulders, upper chest, and upper arms of anyone suited up in it.
The "armor" never really appeared on the battlefield. Ed wore it in the basement when they were getting ready for the battle, and Eddy wore it during the battle, but the suit was never actually used. This is due in part to the fact that there were no "aliens" with heat vision, and in part due to the fact that Eddy stayed out of the battle until he had a chance to use his weapon.