Fosfor

Fosfors are consumable Fishing Gear items, which upon use launches a bright glowing flare into the sky. This not only acts as a visual marker that allies can see to note the player's position, but it also increases that player's Affinity range for 2 minutes, allowing affinity earned by that player to reach allies much further away.

There are two types of Fosfors available, though the only difference between them is the color of the flare launched.

Acquisition
The reusable Fosfor blueprints can be bought from Nakak in Cetus. The actual price of buying the blueprints changes daily, though the payment will always be in Plains of Eidolon-exclusive resources.