International Fixed Calendar
The International Fixed Calendar (also known as the Cotsworth plan, the Cotsworth calendar, the Eastman plan or the Yearal) was a proposed reform of the Gregorian calendar designed by Moses B. Cotsworth, first presented in 1902. The International Fixed Calendar divides the year into 13 months of 28 days each.
Source: Wikipedia — International Fixed Calendar (CC BY-SA 4.0)