People just realised some iPhones have a strip on the top but others don’t, and here’s why

A tweet has gone viral this week asking what on earth that strip on the top of an iPhone 17 is for, and it’s got everyone majorly confused, because some people have it and others don’t. Here’s why it’s there, and why some iPhones don’t have it, even though they’re exactly the same model. 

Hey @grok, what is that on the top part of the iPhone 17 Pro? But why doesn't my iPhone 17 Pro have that? pic.twitter.com/1AhvAFMxfq

— Chaudhary Rohit Singh Yadav Office (@OfficeOfCRSY) September 3, 2026

Here’s what that strip on top of some iPhones is actually for 

The strip runs along the top edge of some iPhone 17 Pro Max models, and it’s there to help your phone get 5G signals. It’s only on select models of the iPhone 17 Pro and iPhone 17 Pro Max sold in regions that use a certain type of 5G called 5G millimetre-wave (mmWave), mainly in areas of the United States and Canada.

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5G mmWave is used in some 5G wireless networks to deliver ultra-fast speeds and huge data capacity over short distances. The whole thing is a bit techy, but the metal and aluminium enclosure of the iPhone 17 blocks these high-frequency mmWave 5G signals from passing through freely. So, Apple added a small cutout that’s non-metallic so that this high-speed data can pass through. 

As nicely explained by Grok: “That strip on the top edge is the mmWave 5G antenna window. US (and a few other) models include it so high-frequency 5G signals can pass through the aluminium unibody. Non-US models skip it because they lack mmWave support, so your iPhone 17 Pro simply doesn’t need or have the cutout.”

If your iPhone 17 doesn’t have this, the area where you live doesn’t have mmWave 5G infrastructure, so it’s just not needed. On previous models like the iPhone 12, 13, 14 and 15, this strip was on the side edge, not the top. But Apple moved it so people don’t accidentally cover it with their hands. Now you know!

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Featured image credit: Twitter