Attractive, functional, affordable and better than what I made myself.
Positive Product Points
You won't be embarrased to have it next to your $1500 espresso machine. No slip base prevents it from moving while knocking the PF. Dishwasher safer, and no-rust stainless construction. It's not too expensive.
Negative Product Points
Could stand to be a little larger. The rod ends become loose from time-to-time. The rubber on the rod may not hold up very long. The grommits holding the rod in place get cut in half from the impact of the portafilter.
How much is there to say about a knock box? It's just a receptacle to dump spent pucks into, right? That's what I thought when I fashioned my first knock box from a plastic hardware bin. It's didn't take long for me to figure out that there was more to a knockbox than a place to hold spent pucks.
I purchased the "Home Style Knock Box" from espressoparts.com because it was good looking and reasonably priced. It has a heavy, removable rubber base that keeps it from moving in use. It has a steel rod with a rubber coating to protect your portafilter from damage. It's high sides prevent splatter. The box is rust-proof and dishwasher safe. And on top of all that, I think it's fairly attractive.
On the down side, there are a few points. First is the size - it'll hold pucks from about six double shots. Another concern is how quickly the rubber bar seems to be wearing - I expect it to hold up well for a year or two. The grommits holding the rod in place will last less than that, but are replaceable for pennies from any reasonably stocked hardware store. The only other real pet peeve I have is that the rod ends come loose occassionally and must be hand tightened. No big deal.
Overall, this box is functional, attractive and economical.
Bought online from espressoparts - an unremarkable experience that met expectations.