The Valjoux 555 watch movement is a mechanical, manual-winding chronograph movement that was commonly used around 1945. It features a Breguet hairspring and is built with different pillar plate sizes, including the 285, 287, and 288. This movement incorporates a pillar wheel and offers various functions such as a 60-second chronograph, sub-seconds, and a 30/45-minute chronograph option. Additionally, it provides an optional 12-hour display like the 285 model.