To spite the name, a knock box is anything but sexy. It's just a box with a padded bar across the middle that you knock your portafilter against to clear the spent coffee grounds out of it. It's just a customized waste receptacle.
Well, the Grindenstein Knock Box got great reviews on CoffeeGeek, and I got tired of fishing my filter basket out of the trash, so I ordered one. $28.95 delivered from Australia! I ordered it because it's small, cheap, has good reviews and isn't hideous. But sexy? Well, no.... but here's a great add from Grindenstein to make me think differently!