A fake Type 21 flyback is a replica of the Breguet Type XXI 3810, the 42mm automatic chronograph with a flyback function. "Type 21" is simply how most people type XXI into a search bar, so you will see the same watch listed as Type XXI, Type 21, or just 3810. The one question that decides whether a replica is worth your money is this: does the flyback work, or is the lower pusher decorative?
Short answer, and it is not a comfortable one: on most replicas under a few hundred dollars, that pusher is decoration. The watch is built on a 7750-family automatic chronograph, which has no flyback mechanism at all. Press the lower pusher while the chronograph is running and either nothing happens or the movement fights back. A real flyback resets to zero and restarts in a single press, without ever stopping.
What the genuine flyback actually does
On the real Type XXI, the flyback (retour en vol) exists so a pilot can time one leg of a route and start the next without losing a beat. One press of the lower pusher zeroes the chronograph and immediately sets it running again. Breguet built the watch around its caliber 584Q, part of the Lemania 1350 family, a self-winding flyback chronograph with a 24-hour day and night indicator and a date. The other signature is the oversized central chronograph minute hand, which makes elapsed minutes readable at a glance instead of from a tiny subdial.
Why replicas skip the flyback
Flyback costs money to build. A proper one needs a heart piece and a way to drop the reset hammers while the gear train keeps spinning, plus an isolator so the two events do not crash into each other. The 7750 layout has a reset hammer but no safe way to reset while running. So the factories take the cheap road: they keep the correct pusher position and the correct look, and they leave the mechanism out.
A handful of higher-priced reps claim a modified flyback module. Treat that claim as unproven until you test it yourself.
The ten-second flyback test
- Start the chronograph and let it run 20 to 30 seconds.
- Leave the running hand sitting mid-dial, nowhere near zero.
- Press the lower pusher once, while the chronograph is still running.
- True flyback: the hands snap to zero and start counting again from zero in the same press.
- 7750-based replica: nothing moves, the pusher feels dead, or the chronograph stops and needs a second press to restart.
Run that test on any watch you already own, or in front of a seller before money changes hands. A seller who will not let you press a pusher has answered your question already.
What you will usually find inside
- Asia 7750 automatic. Correct subdial count, correct pusher positions, no flyback. This is the default.
- 7750 with a 24-hour module stacked on top. Keeps the day and night subdial but adds height to the case.
- Occasionally a hand-wound movement with a decorative rotor screwed to the back. It winds only through the crown, and the flyback is still absent.
Case thickness is a useful tell. The genuine Type XXI sits in the 13 to 14mm range. If a rep measures past 15mm, there is a module in there doing work the original does with a purpose-built movement.
Dial and case tells beyond the movement
- The case band should be fluted with crisp, evenly spaced coin-edge ridges, not soft bumps.
- The guilloché dial should be engine-turned so the pattern shifts as you tilt it under light. Printed texture looks flat from every angle.
- Breguet hands should be thin, sharp, and evenly blued or polished, with no visible tool marks at the tips.
- The date window should be cut cleanly with the numeral centered, not leaning against one edge.
- Case size checks out at 42mm, with welded lugs and sapphire on both sides.
Before you buy
Ask for a video of the flyback test, filmed in one take with a running chronograph. Ask what movement is inside and whether it is automatic. Ask for a straight-on dial photo and a side profile so you can judge thickness. Then price it against what a 7750-based chronograph should cost, not against what a genuine 584Q costs. A replica with an honest 7750 inside and no fake flyback claim is a known quantity. A replica advertised as a true flyback at a bargain price is a story, and the pusher is where the story falls apart.