VitraPOR® is the brand name for a complete line of sintered filter - elements. ROBU® products represent the internationally established type of borosilicate glass 3.3, like DURAN©, PYREX©, SIMAX© and ILMABOR© according to......VitraPOR® is the brand name for a complete line of sintered filter - elements. ROBU® products represent the internationally established type of borosilicate glass 3.3, like DURAN©, PYREX©, SIMAX© and ILMABOR© according to DIN/ISO 3585, american, english and french standards. Highly technological manufacturing processes secure the quality of the ROBU® sinter-products already during production and guarantee uniform properties even for the highest demands and exacting applications.