This is a desiccant holder that looks like a big pill. It is made to fit inside a filament spool, but I am sure it will fit in other places.
It is modeled in two pieces and threaded. You can load the pill by separating the two pieces or by stuffing it through the sides.
The male threaded side will need some support.
If you use it in a dryer, be sure use ASA or equivalent due to the high temperature exposure.
For more information you can watch the attached video: