Publisher Summary This chapter presents the numerical data and the simulated powder patterns of (Cs, K) ZK5, dehydrated material with zeolite framework type code KFI (recognized by IUPAC Commission on Zeolite Nomenclature) and 15° as 2θ value. Two compositions, which are expressed in terms of the full unit cell content, are provided. The chemical composition is the nominal material composition provided in the original reference, and is usually obtained from chemical analysis. The refined composition is derived from the structure refinement. Crystal data include lattice parameters and space group information from the International Tables for Crystallography, 4th revised edition 1995, and incorporates the new e-double-glide plane. The type of refinement, along with the final R-values, is listed with the unit cell parameters. Reference cites the literature from which the crystal data, atomic coordinates, and temperature factors are obtained. The powder diffraction data include the 2θ values for CuKα radiation, d-spacing, relative intensities (Irel), Miller indices (h k l), and multiplicity Mhkl, for the strongest reflections with an integrated intensity Irel greater than 0.1. The strongest reflection is set to Irel = 100. The powder patterns for CuKα radiation are reproduced from 0° to 50° 2θ. The intensity range is plotted between 0 and Imax = 80. The scale of the ordinate is calibrated in percent relative intensity of the maximum peak height and the peak intensities in the plots are not identical to the integrated intensities listed in the corresponding tables, because of the overlapping diffraction peaks.