The MSR D7 is an open face calibre watch movement that was introduced in 1910. It features a Breguet hairspring and incorporates an intermediate wheel between the minute pinion and the rest of the train, allowing for a low profile without compromising sturdiness. The movement derives its name from the arrangement of its four train bearings, which corresponds to the four brightest stars of the Pleiades constellation. The 7521 movement is known to have an optional Chronometer certificate from the Neuchatel Observatory. It offers stem winding and setting functionality, along with a sub-second display. The specific differences between the 17'''10, 701, 703, and 7521 variations of the movement are not known.