Before purchasing the Caldera Cone system for either the BPL Firelite 550 or 900, please study the pictures below to ensure it will fit. BPL originally produced a versions of the 550 and 900 Firelite from a company called King Sound. In November 2010, BPL changed vendors and pot dimensions but kept the Firelite 550 and Firelite 900 names. The later version is dimensionally similar to the Evernew 500 and 900 Mug Pot UL (part numbers ECA266 and ECA267) mug and will require a different size cone.
The way you can tell which pot you have is: