Fig. 6. If portions of two similar circles are cut off, each with a different base, the portion depicted in B, which has a larger base (14.5 mm), will have a greater sagittal depth or vault than the portion depicted in A, which has a smaller base (13.0 mm). (Stein HA, Slatt BJ: Fitting Guide for Rigid and Soft Contact Lenses: A Practical Approach, 2nd ed. St. Louis, CV Mosby, 1984)