Three possible answers
Every time we find the same gadget under another name, it goes into one of three boxes. There is no fourth.
- Confirmed twin
- The FCC ID or the model number matches, and so do the specs and the factory photos. Only the brand on the box changes.
- Near twin
- Same design and nearly everything else, but one thing changed: a smaller battery, a different sensor, one accessory fewer. The product page tells you exactly what.
- We don’t list it
- If it only looks the same from the outside, or we couldn’t compare the factory details, it doesn’t appear. We never calculate a saving against something that isn’t the same.
The FCC ID: a gadget’s fingerprint
In the US, anything that transmits by radio (Bluetooth, Wi-Fi, cellular) needs approval from the FCC, the federal communications agency. With the approval comes a code, the FCC ID, printed on the gadget’s label or its box. The first characters identify the manufacturer.
Two gadgets with the same FCC ID came from the same approved design, whatever the box says. For example, the A40 Pro earbuds carry 2BCF9-A40PRO on both Amazon and AliExpress. Of the 13 gadgets we cover, 10 have an FCC ID.
Beyond the FCC ID we compare the model number, the specs each listing gives (input, battery, Bluetooth version…) and the photos: when a seller uses the manufacturer’s photos, we recognize them.
On every product page, The proof puts the two listings side by side and marks each detail = if it matches, ≠ if it doesn’t, and ? if one of the listings doesn’t say.
When there’s no FCC ID
A cable, a charger without Bluetooth or a car mount doesn’t transmit anything, so it has no FCC ID. We say so on the product page, and the proof rests on the model number, measurements, weight and photos. If that isn’t enough to be sure, the product stays out.
How we count savings
- Always with shipping to the US included. A price without shipping is a trick.
- Savings are measured against Amazon’s price, and only for confirmed twins. Near twins are shown, but they don’t count toward the headline saving.
- Amazon’s price carries the date and time we saw it, and it may change. If Amazon doesn’t give us its price, we don’t invent a saving: we send you to check it there.
- eBay prices are refreshed at least every 6 hours and other stores at least once a day; every price says how long ago we saw it.
- Paying less almost always costs something: days of waiting, a harder return, less warranty. That’s why every product page has Win some, lose some, with the math on how much you save per day of waiting.
Why there’s no Amazon history
Amazon’s affiliate program rules don’t allow showing its price history or sending alerts when a price drops. So our charts only show AliExpress, eBay, Walmart and other stores that allow it.
How we make money
If you buy through our links, the store may pay us a commission. Your price stays the same. We earn more at some stores than others, but that doesn’t change the order: the cheapest identical twin always comes first, even when we earn less there.
As an Amazon Associate I earn from qualifying purchases.
Our links go straight to the store, with no redirects of our own, and they’re marked as sponsored for search engines.
Demo data
This version of the site uses made-up data to test the design: the brands, sellers, FCC IDs, ASINs and prices aren’t real. The last simulated update was Sep 23 at 3:40 PM ET.