Our PEI (Polyether Imide) filaments are made using ULTEM™ PEI resin from Sabic.  PEI is inherently flame retardant with a UL V0 rating based on it's chemical structure and requires no additional additives to achieve this flame rating.  

Print ULTEM™ PEI with Gearbox™ HT2 High-Temp 3D Printer.  Check it out HERE. 

ULTEM™ is a registered trademark of Sabic Innovative Plastics.