Longines 18.89N, 80Z, 19.89N (18, 19'''), Balance staff, Ronda: 1607
- Manufacturer Ronda no: 1607
- Total length: 435
- Fits cal: 18''' 18.89N, 80Z
- Fits cal: 19''' 19.89N
- A: = 435 (ronda A).
- B: = 221 (ronda B).
- F: = 80 (ronda K).
- G: = 125 (ronda J).
- H: = 63 (ronda G).
Conversion: Ronda to DCN
- A = A
- B = B
- J = G
- G = J
- K = F