The Reinforced Underlay is an upgrade in XCOM 2: War of the Chosen that is activated upon the completion of the ADVENT Purifier Autopsy research.
In-Game Description[]
“ | The ADVENT Purifier armor features a number of improvements designed by ADVENT to enhance their tolerance of environmental hazards. We've mirrored some of these changes to increase the durability of our armor underlays. All vest utility items now provide an extra +1 health. | ” |