Size exclusion chromatography (SEC), gel filtration chromatography (GFC) and gel permeation chromatography (GPC) are chromatographic techniques based on discrimation by differences in the size of the analytes. GFC uses an aqueous mobile phase and GPC an organice phase. The general term SEC covers both uses. \ Tosoh manufactures two distinct product lines for GPC of organic-soluble polymers. While each line is based on particles prepared from polystyrene crosslinked with divinylbenzene, they differ in degree of inertness, and operating temperature range. TSKgel Hxl-type, SuperHZ-type, and SuperMultiporeHZ-type columns are most inert to sample adsorption. TSKgel Hhr- and SuperH-type columns provide minimal shrinking and swelling of the column bed when changing solvents and allow operation up to 140°C. Small particle, narrow bore TSKgel SuperMultiporeHZ, SuperHZ and SuperH columns provide high efficiency, short analysis times and operating cost. Except for TSKgel SuperMultiporeHZ columns, all other TSKgel H-type column lines contain at least five different pore sizes. Each product line contains columns for the analysis of oligomers to polymers containing molecular weights as high as as 4 x 10^8 Da (estimated). All product lines contain a number of linear columns that are prepared by blending particles with different pore sizes.