Measure the outside diameter of the cartridge (in inches, +/- 1/32").
Measure the cartridge length (in inches, +/- 1/16") including end caps but excluding any handles or other extensions. Unicel recommends measuring through the center (if possible) rather than along the outside edge.
Identify the cartridge outside edge end cap configuration using the photograph chart. If the top and/or bottom is "open," measure the inside diameter (in inches, +/- 1/32") of the top and/or bottom.