Sistem51-M HMS

The SISTEM51 Manual-Wound Small Seconds is a hand-wound mechanical movement powering the Savonnette-style Audemars Piguet × Swatch Royal Pop models. It utilizes the standard SISTEM51 architecture with an added small seconds display at 6 o’clock, 15 patents, a Nivachron hairspring, and a 90-hour power reserve adjusted by laser. The barrel drum serves as a power-reserve indicator, showing grey for low power and gold for a fully wound state, and is viewable through the transparent case back.