Despite its case diameter of just 36.8 mm, this model incorporates all the hallmarks of the Lange 1, condensed with technical features including a twin mainspring barrel providing a 72-hour power reserve, an UP/DOWN power-reserve indicator, an outsize date display with instantaneous switching, and a balance wheel with eccentric poising weights and a proprietary balance spring. Often referred to as the "Little Lange," this model retains the iconic design of the original Lange 1 in a smaller case size.