A plain tube column with hempel indentations at the bottom for packing support.Column is fitted with standard taper joints. The column along with the top joint is enclosed in a vacuum jacket. The jacket is silvered except for two narrow strips 180° apart which act as viewing windows. Jacket is also equipped with expansion bellows as to allow for the difference in temperature and expansion between the column and the jacket. Overall length of the column is approximately 200 mm longer than the column length shown. This is an average and depends on the size of joints used.