Perkomax Percolator Inner Cup Keep your Petromax coffee percolator brewing. The inner cup for the enamel percolators #100029485 (per-9-s) and #100029486 (per-9-w) is available as a spare part. The three-part set consists of a tube and a filter with lid and is made of stainless and durable steel. Thus, you can brew strong coffee and aromatic tea on the way to enjoy your adventure time even more.