The 2135 is the first minute repeater wristwatch that is water-resistant to 30 m. It is fitted with an exclusive Blancpain-patented locking mechanism which seals the case. When it is open, the valve on the left side frees a spring inside that enables the repeater mechanism to be wound. To ensure total water-resistance, though, it must be closed. This blocks the repeater mechanism. This exceptional watch has a yellow gold case from the 2100 line and is fitted with the famous automatic 0035 movement launched by the brand in 1988, one of the smallest and flattest of its kind.