Hi this is a brass shavings basket or brassket some call it.  (red in color)

For the Forster case trimmer.

Catch your brass shavings in the basket to avoid a messy work area.

Two piece design. One piece slips on the trimmer base, and the other basket part is held on with very strong magnets.

Very easy to just remove the basket and empty when needed, due to the magnets.

NOTE: Does not work if you have the 3 in 1 cutter  

This item is 3d printed by me. 

Thanks for looking.

Trimmer not included. Just the 3D printed parts