Star Wars Rare Sandtrooper backpack part

I have available a nice rare backpack part as seen on the Sandtrooper backpack.
This part is seen on the lower box on the exhaust port back.
I don't recall seeing these ever previously being available, but could be wrong?
I am looking for £200 plus postage for this rare part.

 

[dindjarin22]

What is it?

 

[Marv]

The lower box used here

As seen with the other found tray

 

[dindjarin22]

Pm’d