3712 & 5712

Can you see the difference?

The left is the old model 3712, and the right is the current 5712.

The 3712 is a short-lived model with a manufacturing period of one year or less. The design differences are the thickness of the numbers on the lower left date display, the shape of the 6 o'clock index, and the design around the crown.

As you can see from this, the design balance has improved. Structurally, the 3712 is the biggest feature of the original two pieces.