Multi-cored life support. – Increases O2 capacity by 25 and improves O2 consumption rate by 20% each for every equipped Support Relay in the party.
The Support Relay is a powerful oz kit early in the game providing gun damage per unit of O2 at a rate over twice its level along with a large capacity.
As Gun Damage per O2 does not seem to increase past 0.17% at level 50, this oz kit stands out early game.
The Support Relay becomes exceptional when the whole party has it equipped, adding 75 capacity and reducing the rate at which oxygen drains by 60% with a full party. As the maximum O2 capacity is increased, that means more percentage damage can be achieved providing 3.75% maximum gun damage for each additional party member with a support relay.
Although the Support Relay is a legendary, it is treated as a unique item and can only be obtained as a mission reward.