Longines 18.68Z, 18.69Z, 19.69Z (18'''), Balance staff, Ronda: 921
- Manufacturer Ronda no: 921
- Total length: 482
- Fits cal: 18''' 18.68Z, 18.69Z, 19.69Z
- A: = 445 (ronda A).
- B: = 252 (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