Most of these programs designed for proteins and cages utilize a rolling probe algorithm, typically using one or two probes. The one-probe algorithm is best suited for cavities with small windows, which are the apertures within a cage structure connecting its enclosed cavity with the external environment. This algorithm defines the cavity as the volume enclosed by a probe "rolling" around the entire cage structure without escaping (Figure ). However, a limitation of the rolling one-probe algorithm is its failure when the probe's radius is smaller than the cage's windows, causing the probe to escape and leading to an overestimation of the volume. This problem can be solved by increasing the probe size to prevent it from escaping, but this underestimates the cavity volume as the gaps between the probe and the atoms of the cage are larger.