The Junghans J91 is the little sister of the Junghans J90, nevertheless it is dressed as shown above in a classic men's wristwatch case. The pictures show the comparison for Junghans J90 (shown at left, easily recognized by the larger movement of J90 and J91 on the lack of a second hand) .
The caliber Junghans J90 and J91 are the only built by Junghans watch movements with cylinder escapement. At that time it was thought that many watchmaker comes cope more easily with a simple cylinder escapement.
Here in comparison a Junghans J91 mens watch (left) and a Junghans J91 ladies watch (right).