These jacketed distillation columns have a row of indentations at the base to support column packing material. The jacket reduces temperature fluctuations and also allows the column to be used a a water-cooled condenser. The column length listed is for the straight portion above the row of indentations and below the joint. Each column has a standard taper top outer and lower inner joint. Lengths of 110 or 200 mm are available. All inner diameters are approximately 10 mm.