This is a knock box shield that fits the 6" version of the Rattleware Stainless Maple Holder Knock Box. I've had this knock box forever, but it always threw coffee grounds all over the walls and counter. I finally came up with this shield which works wonders. It contains all of the mess from knocking espresso pucks out of the espresso basket.

https://www.amazon.com/Rattleware-Maple-Knock-Box-Set/dp/B0061TXLUU?th=1&tag=seriouseats-onsite-prod-20&ascsubtag=7112160%7Cn7d4d0375dc394ad6a6e705723abc35c117%7CB0061TXLUU%7C1754241915851%7C%7C