La Marzocco Group Head Screen Screw
6 x 16 mm stainless steel with holes. This acts as the diffusor (vite di diffusore) in the La Marzocco group heads. Old version, to be phased out.
If you want to have a great screw, go for this!!! Seriously though, it's the manufacturer's screw for the screen. It fits fine, and works fine. I got a spare so next time one shears apart I will not be done for a few days. The original screw sheared apart after ~ 7 years.