This is the official reusable filter, developed by the people behind the world famous Aeropress brewer.
Made from premium grade stainless steel, the holes are 178 microns. This has been designed to stop the grounds, but allow oils to pass through, giving a rich full bodied brew.
If you've never used a metal filter before, you might want to consider grinding a bit coarser than usual and leaving the coffee and water together for a bit longer. We find that metal filters give a different result to paper ones. It's also a great way of eliminating paper waste from your brewing routine.