The Normcore Puck Screen is a stainless steel accessory for portafilters that enables you to improve espresso extraction. Generally, puck screens prevent channeling by evenly dispersing water across their mesh to ensure a balanced extraction. After tamping, place the puck screen over the grounds, insert the portafilter as you normally would, and pull your shot. This premium puck screen from Normcore also keeps your baskets and machine cleaner by creating a barrier between your coffee and the group head. This means a faster workflow between shots as well as less cleanup. Combined with good puck distribution and tamping, we enjoyed how our espresso shots had a softer acidity when using this screen. The manufacturer recommends thoroughly washing the steel screen with hot water after each use. Clean stains with Cafiza or CaffeNu detergent and perhaps apply a few blasts from your steam wand to dislodge any grounds. Normcore Puck Screen features Encourages even distribution during extraction Reduces channeling in the puck Fits most espresso machine portafilters Keeps espresso machine group heads cleaner Normcore Puck Screen specifications Diameter: 58.5mm Material: 316 stainless steel Filtration mesh size: 0.8mm thick