Beneath the screen, seen here with the tube protruding, is a woven layer approx 8-10mm thick, below that is a 30-40mm layer of tightly packed desiccant beads. Then another layer of woven filter followed by another fine screen. The top layer of woven material usually loads up with small metallic particles. Clean (polished) contents exit through the tube.

Change the dryer after a short run as good insurance. It's cheap and you can reuse the recovered freon.