Short answer
The IW371615 is an IWC Portugieser Chronograph 41 in stainless steel with calibre 69355 inside. A replica of it copies that case and dial layout. Most replicas use an Asian 7750 or a 7750 with engraved plates sold as a "clone 69355." The 7750 is taller than calibre 69355, so many copies measure 14 mm to 15 mm thick against 13.1 mm on the original. Ask the seller for the movement name, a caliper photo of the case, thickness, weight in grams, and a timegrapher reading before you pay.
The real IW371615
IWC lists the Portugieser Chronograph 41 line with a 41 mm steel case, 13.1 mm thick, sapphire crystal on both sides, and 3 bar (30 m) water resistance. The dial has a printed minute track, Arabic numerals at 12 and 6, applied indices elsewhere, and two subdials stacked at 12 and 6. There is no date window on this line.
Movement: calibre 69355, made in-house. Automatic winding, column wheel chronograph, 46 hours power reserve, 28,800 vph (4 Hz). IWC replaced the older 79350-based calibre with the 69355 when it refreshed the line in 2020.
Dial color and strap change with the reference number inside the same line. I cannot confirm the exact dial and strap combination sold under IW371615 from memory, so compare photos of the specific listing to the IWC product page.
Where replicas differ
Movement
Common options are the Asian 7750 (A7750), a decorated 7750, or a 7750 with engraved bridges sold as a clone. Calibre 69355 uses a column wheel; the 7750 uses cams and levers. Pusher feel and reset feel differ. Both run at 28,800 vph, so the beat rate matches.
Case and crystal
Measure the case with calipers. Target 41.0 mm. Target lug width 20 mm. Check thickness: 14 mm or more points to a 7750 inside. Look at the crystal edge from the side. Thin copies show a flat edge with no dome.
Dial and hands
Subdials must sit at 12 and 6 in a vertical line. No date window. The minute track is printed, not applied. Hands are leaf-shaped and blued. After a chronograph reset, subdial hands must return to zero.
Case back and strap
The display back shows the movement. Factory engraving is crisp. Many replicas use laser etching with a dark edge and shallow depth.
Checks before you pay
- Timegrapher photo: rate, amplitude, beat error.
- Caliper photo of case diameter and thickness.
- Photo of the movement with the back removed.
- Start, stop, and reset the chronograph three times.
- Treat any water resistance claim as untested. Do not swim with it.
- Return window and a payment method with buyer protection.
Price
Replica pricing runs in tiers. Listings sit from about $150 to $700. IWC list prices and used IW371615 prices move with the year and the currency, so check iwc.com and Chrono24 for current numbers.