Similar to Destiny 2 with Xur, The Division 2 has a vendor named Cassie for particularly valuable gear. She spawns randomly at specific times in the game world but only under certain conditions.
This is “the Xur” of The Division 2: Cassie is referred to as the “Gun Runner” and is a gear vendor in The Division 2. She apparently carries particularly valuable gear, as revealed by the developers in the State of the Game from March 6.
However, Cassie is not a normal vendor with a fixed location that you can always return to. There are a few conditions to unlock her.

This is Cassie, the “Xur” of The Division
Why the comparison in the first place? Xur is a vendor in Destiny 2. He regularly has exotic gear available, and his offerings rotate weekly. He appears on Fridays and disappears after a few days.
Similarly, Cassie behaves. She does not have a fixed point where you can find her. She appears at one location and then moves on to the next random spawn point. With Xur, you also never know at which of his locations he will spawn.

Where exactly these positions of Cassie are located is still unclear. But to unlock Cassie at all, you need to fulfill two conditions.
This is how to unlock Cassie: To activate her spawns, you need to
- first find a certain person during the story
- and reach Level 30.
Once you meet these conditions, Cassie will appear at regular intervals at different locations in the world.
How often does Cassie spawn? In the State of the Game, it was mentioned that there are about one and a half days between each spawn. The spawn times may be adjusted to the respective time zones so that nobody has to get up at night.
What does Cassie offer? Similar to Xur, Cassie offers an exotic weapon every week. Additionally, there seems to be other gear with above-average stats.
It is not known whether the offerings are limited to exotic weapons or if there can also be exotic gear.

How long does the offering last? In the stream, it was mentioned that the offerings rotate approximately every week. It is not known what currency you will have to use to pay.
What do you think of Cassie? Does the concept fit with The Division 2?
Xur is not the only one that The Division takes inspiration from Destiny: