This mesh is for the true pourover coffee lover, and will help take your brews to the next level. This mesh sits between the filter and the bottom of a pourover brewer, and prevents the filter from collapsing on the holes. This makes brew times much more repeatable! Customers report smoother flow, no more stalling, and sweeter, cleaner brews. Without this mesh, filter papers will often collapse over the holes in flat-bottom brewers, stalling the brew. This can cause brew times to vary wildly, sometimes longer than 6 minutes. This mesh is 44.5mm in diamater, fitting a variety of flat-bottom pourover brewers. Known Compatible Brewers: -Fellow Stagg X -Fellow Stagg XF -Kalita Wave -Blue Bottle Dripper Handmade out of a food grade aluminum mesh. Thank you for supporting my American Small Business!