Hamilton H76409530 Khaki Aviation Pilot Pioneer Mechanical ChronoProduct Overview The "Khaki Pilot Pioneer Mechanical Chronograph," featuring a unique vintage military aviation design, revives the form and function of chronographs manufactured for British Navy pilots in the 1970s. This robust and reliable 40mm case watch is equipped with Hamilton's proprietary hand wound movement H 51 Si. Specifications Product Number H76409530 Caliber H 51 Si Collection Khaki Aviation Movement Mechanical Function Chronograph Case