The Khaki ETO (Estimated Time Over) embodies Hamilton's passion for aviation and his obsession with precision. ETO makes calculations to help you plan your trip - just rotate the bezel to mark the appropriate speed, desired arrival time or travel time. Official aviation regulations stipulate a five-minute tolerance for ETO: Hamilton does not. Caliber: H-21. The H-21 is a powerful automatic chronograph movement with an enhanced 60-hour power reserve, making it perfect for the needs of the sportiest models. The H motif on the oscillating weight leaves no doubt about who made this movement.