Kippenhahn diagrams of the best-fitting models for KIC 9145955, KIC 9970396, KIC 9882316, and KIC 11968334. Regions where convection takes place are hatched. Regions where nuclear burning produces more than 1 erg/(g × s) are shown in gray for hydrogen burning. The vertical blue dashed lines in both panels indicate the age at the end of the main-sequence stage, that is, when the core hydrogen mass fraction is about 0.01. The vertical red dashed lines in both panels indicate the current age of KIC 9145955, KIC 9970396, KIC 9882316, and KIC 11968334, respectively.