The Ultimate Cheat Armor is a piece of chest-armor added by GregTech 4. It is creative-only. It combines the effects of the QuantumSuit, Cloaking Device, Light Helmet, plus breathing under water, automatic food generation, and many other benefits listed in the tooltip.
Although the tooltip notes it can store 1,000,000,000 EU, it can actually store infinite, like the Debug Item.