Short answer
IW371640 falls in the IWC Portugieser Chronograph line. The watch is 41.0 mm wide, 13.1 mm tall, steel, with two subdials, sapphire front and back, and the in-house 69355 automatic caliber. Replicas sold under this number copy the outside. None carry a 69355. Most use an ETA 7750, an ETA 7753, or a Seagull ST19, and the case runs 0.5 mm to 2 mm thicker than the original.
What the reference covers
IWC builds the 3716 case in steel and in red gold. The dial has applied Arabic numerals, leaf hands, a printed minute track, a small seconds subdial at 6 o'clock, and a chronograph minutes counter at 12 o'clock. There is no date window. Strap is 20 mm alligator on a pin buckle or folding clasp. Water resistance is 30 m, which covers rain and hand washing, not swimming.
Public records for the exact IW371640 dial and strap combination are thin. Sellers attach the number to several 3716 variants. Confirm the dial color, index finish, and strap code against IWC's own catalog before you compare a replica to anything.
Specs to compare
- Case: 41.0 mm diameter, 13.1 mm height, stainless steel
- Lug width: 20 mm
- Crystal: sapphire, front and case back, anti-reflective coating on both faces
- Movement: IWC 69355, automatic, 28,800 vph, 46 hours power reserve
- Subdials: chronograph minutes at 12, small seconds at 6
- Strap: alligator leather, 20 mm, steel buckle
Movement inside replicas
The ETA 7750 beats at 28,800 vph and drives a 12 hour chronograph counter. Replica builders rotate the movement or fit a module to move that counter. The 7753 is a 7750 with the minute counter shifted, which suits the 12 and 6 layout. The Seagull ST19 is hand wound, beats at 21,600 vph, and needs daily winding. A few builds use a decorated 7750 with a plate and rotor engraving designed to read as a 69355 from the back.
Watch the pusher feel. A 69355 starts and stops with light pressure and resets in one snap. A worn 7750 grinds on reset. A quartz replica has a ticking central hand and no chronograph sweep at all.
Checks on the case and dial
- No date window. A date at 3 o'clock means the base is not a 3716.
- Case height under 14 mm at the crystal. Many builds sit at 15 mm or more.
- Crown engraving: the IWC Probus mark, crisp, centered.
- Leaf hands: polished bevel down the center, flat sides.
- Subdial rings: printed, thin, aligned with the applied numerals.
- Case back: reference number and case number stamped in a straight line, not laser dotted.
Price bands
Three bands show up in listings. $80 to $150 buys a 7750 build with a mineral crystal and a soft dial print. $250 to $450 buys sapphire on both sides, a decorated 7750, and sharper dial printing. $500 to $700 buys a slimmed case, hand-finished edges, and a closer dial. No band includes a 69355, and no seller can supply one at these prices.
Red flags
- Catalog photos of a genuine watch with no photo of the actual unit.
- Quartz movement described as automatic.
- 42 mm or 44 mm case claimed as 41 mm.
- Water resistance claims above 30 m with a push-in case back.
- No case back photo, no movement photo, no strap code.
Legal note
Replica watches are counterfeit goods. U.S. Customs and Border Protection seizes them at the border, and the importer loses the shipment and can face a penalty. Trafficking in counterfeit goods carries criminal penalties under 18 U.S.C. 2320. Trademark owners can also file civil claims under the Lanham Act.
Checklist before payment
- Ask for photos of the case back, crown, and clasp on the actual unit.
- Confirm the dial has no date and the subdials sit at 12 and 6.
- Ask which movement sits inside and at what beat rate.
- Measure the case height in the seller photo against a known object, or ask for a caliper shot.
- Confirm the strap is 20 mm and the buckle matches the case metal.
- Pay by a method with a dispute process. Bank transfer has none.