What is the difference between caliber 5040.B and 5040.D?
There are two variations of the Ronda 5040 including the 5040.B and 5040.D. Side by side the specs are identical between these two movements. The difference is the way the calendar is displayed. The 5040.D has a regular date while the 5040.B offers a big date. The back of the movements look exactly the same (except for the B and D in the caliber number). Ronda even uses the same picture of the backs on their site.