How it works. Porcelain filter shown inside a carafe (right). Charcoal pods shown on the left. Optional wood collar shown atop the carafe. (The filter, inside the carafe, looks transparent in this picture.) All filters are held in place with an inner groove and nub that allows it to be easily slid into place. The wood collar is an optional stay. Optional green silicone rim. All filters are held in place with an inner goove; the collar is an optional stay.