For column selection of up to 8 columns. Only for use in II Multicolumn Thermostat (G7116B). G7116B: 1300 G4239C: Low-dispersion capillary kit 0.12 mm id, including low-dispersion Quick Connect heat exchanger: G4239C#005: Low-dispersion capillary kit 0.17 mm id, including low-dispersion Quick Connect heat exchanger: G4239C#006