Upper panel: de-projected ring axis ratio versus bar torque parameter, separating inner and outer rings, and highlighting closed rings. Central panel: de-projected ring axis ratio versus tangential-to-radial forces (Q_T) evaluated at the location of the ring semi-major axis. Ringlenses are displayed with different symbols. Lower panel: same as above but separating barred and non-barred systems. The vertical line corresponds to Q_ring = 0.25. For the different subsets the solid lines correspond to the running mean, while the vertical lines indicate the standard deviation of the mean. The Spearman’s correlation coefficient and significance are indicated on top of the uppermost panels.