KBr powder is graded solely by purity standards that are relevant to infrared spectroscopy.  SpectroGrade™ KBr powder is all made from crystal boules that are suitable for IR spectroscopy based upon ICL’s testing standards.  FTIRGrade SpectroGrade™ KBr powder is made from KBr crystal boules that are not quite beam splitter grade material and is defined as material that does not have any absorbance peaks in excess of 1.5%.  FTIR Premium SpectroGrade™ is the equivalent of beam splitter grade material, and it is made from a blend of KBr crystal boules in which peaks range from 0.9% to 1.1 %. XL Ultrapure SpectroGrade™ is a blend of material from rare boules that exhibit absorbance bands under 0.8% and the impurity range goes down to 0.2%.