Short answer
904L is a superaustenitic stainless steel with roughly 23 to 28 percent chromium, 19 to 23 percent nickel, 4 to 5 percent molybdenum, and 1 to 2 percent copper. Rolex uses it for cases and bracelets and markets it as Oystersteel. On a no-date Submariner replica, a real 904L case and bracelet should feel heavier than a 316L build, hold sharper lug and link bevels, and resist pitting around the spring bar holes and crown threads in humid, salty air. Most 904L claims on budget listings are false, so verify the material before paying extra for it.
What 904L steel actually is
904L (UNS N08904) is a low-carbon superaustenitic grade. Its molybdenum and copper content gives it strong resistance to pitting and crevice corrosion, including in chloride-rich environments. It is also soft and gummy to machine, which is why it costs more to cut, polish, and finish than 316L. Standard 316L runs about 16 to 18 percent chromium, 10 to 14 percent nickel, and 2 to 3 percent molybdenum. Both grades are austenitic and essentially non-magnetic in the annealed state.
Why it matters on a no-date Sub
The no-date Submariner is a plain, symmetrical case. There is no date window, no cyclops, and no dial clutter to pull the eye away, so case finishing carries the entire look. 904L takes a brighter, more even mirror polish on the chamfers and a crisper brushed grain on the lug tops. It also holds an edge longer, so the line between the polished flank and the brushed top stays visible after months of wear.
cheap fake rolex sub no date 2025
How to check a 904L claim
- Weigh the complete watch on a digital kitchen scale. A no-date Sub case with an Oyster-style bracelet in 904L usually lands between 150 and 160 grams, while a 316L build runs several grams lighter.
- Press a magnet against the case side. Neither 904L nor 316L should attract it, so a strong pull means plated brass or ferritic steel and the alloy claim is void.
- Turn the watch under a desk lamp at a shallow angle and trace the edge where the polished case flank meets the brushed lug top.
- Look at the inner link edges on the bracelet. 904L machines to a sharper edge, while 316L links often read rounded or slightly soft.
- Inspect the spring bar holes and crown tube threads with a loupe for pitting, rust bloom, or white corrosion spots.
- Wipe the case with a dry microfiber cloth and check your fingers for a metallic, brass-like tarnish smell that points to plated base metal.
- Ask the seller for a photo of the caseback and the clasp stamp code on a scale.
- Compare two examples side by side when possible, because weight and bevel sharpness are easier to judge in a direct comparison than from a spec sheet.
Red flags
- Advertised weight under 140 grams with the bracelet attached
- A case that pulls a magnet
- Lug bevels that look rounded or washed out under raking light
- Rust or pitting at the spring bar holes within a few weeks
- A seller who will not confirm the alloy or show a scale photo
Legal and practical note
904L is a real alloy, but the watch around it is still an unlicensed copy of a trademarked design. Counterfeit goods can be seized at import in the United States and many other countries, and selling them carries civil and criminal exposure. Treat the alloy question as a materials question only, and weigh the risk before spending money.