Not sure that its doing much with our full 6-cup brewing. Could be designed a bit better to prevent sealing, but for 3 bucks i can probably modify it to keep an open channnel.

Really helps when making a large brew.

If you like your coffee in a "particular" way and want to use a Chemex, get this—it solves the Chemex's main flaw. This stops the filter from sagging into the pour spout and slowing your brew time. I should have gotten this sooner.

I've been using my Chemex for a few years, and it has one flaw: the filters sages into the pour spout, the blocked pour spout blocks the airflow, and suddenly, your draw-down time goes way up. This solves that problem, and I'm impressed that Chemex made such an inexpensive solution.

Works great for both the 10 cup model and the pint size. No longer need to worry about paper filter sagging into the pouring spout now!