The coffee filter is made of the highest quality stainless steel material, no paper filter is used; its reinforced steel mesh is very durable for perfect brewing speed; the bottom base will stay put and will not break; the filter has an ultra Fine wire mesh; no coffee grounds will remain in your mug. It's better quality than plastic, ceramic or glass coffee filters, and it's also a reusable coffee filter made of stainless steel coffee filters. Coffee lovers will love this device to add to their selection of brewing methods.