PermeGear vertical glass diffusion cells are the original Franz Cells. Standard orifice diameters are 5mm, 7mm, 9mm, 11.28mm, 15mm, 20mm and 25mm, other diameters are custom. The word “orifice” as it refers to a Franz Cell is the area at the top of the receptor chamber that is exposed to the membrane or device through which transport or permeation is being studied. Corresponding volumes from 5ml to 20ml are standard and are listed under Typical Dimensions. Clamping is achieved through o-ring joints, flat ground (ground o-ring) joints and flat flange joints. We manufacture our own clamps for the most popular Franz Cell models. Our clamps are all stainless steel and are much easier to use than clamps from other suppliers.