If you’ve noticed a tiny line or slit at the very top edge of your iPhone 17 Pro or Pro Max, you’re not alone. Many users mistake it for a hidden button, sensor, or microphone. In reality, it’s an essential part of the phone’s design — and it plays a big role in how your device stays connected.
Why There’s a Tiny Cutout on the Top Side of iPhone 17 Pro/Pro Max
The small cutout is actually an mmWave 5G antenna window. Because the iPhone’s titanium and glass body blocks high-frequency 5G signals, Apple added this window so those signals can pass through. It’s not visible on all models globally — mainly on models sold in regions where mmWave 5G is supported.
Antenna Window Placement in iPhone Pro Models
| iPhone Model | Year Released | Frame Material | Antenna Window Location | mmWave 5G Support |
|---|---|---|---|---|
| iPhone 12 Pro | 2020 | Stainless Steel | Right side (below power button) | Yes |
| iPhone 13 Pro | 2021 | Stainless Steel | Right side (below power button) | Yes |
| iPhone 14 Pro | 2022 | Stainless Steel | Right side (near top corner) | Yes |
| iPhone 15 Pro | 2023 | Titanium | Right side (slightly higher) | Yes |
| iPhone 16 Pro | 2024 | Titanium | Top edge and side blend | Yes |
| iPhone 17 Pro | 2025 | Titanium | Very top edge (centered) | Yes |
Key Notes:
- The shift from side placement (12–15 Pro) to top-edge placement (16–17 Pro) is due to the thinner titanium frame and redesigned internal antenna structure.
- All these models support mmWave 5G, but only in markets where carriers provide it (like the U.S.).
- Non-mmWave models (in some regions) do not have this visible antenna window.
Understanding the Top Edge Component on iPhone 17 Pro and Pro Max
The top edge of the iPhone 17 Pro and Pro Max doesn’t have any buttons or ports. Instead, it houses a small plastic-like window built right into the titanium frame. This design choice is intentional, and it helps your phone maintain fast and stable wireless connectivity.
Top Edge Antenna Window on iPhone 17 Pro and Pro Max Explained
This antenna window enables ultra-fast mmWave 5G networks to work properly. It’s made from a special RF-transparent material that blends into the frame color. You won’t notice it doing anything, but without it, you wouldn’t get blazing-fast downloads when connected to supported 5G towers.
The Purpose of the Thin Slit at the Top Edge of iPhone 17 Pro/Pro Max
While it might look like a design flaw, it’s actually a crucial functional feature. Apple designed this slit to be almost invisible while ensuring top-notch connectivity performance. It does not act as a microphone, speaker, or sensor — its only job is to support wireless signal transmission.
Antenna Window on iPhone 17 Pro/Pro Max and Older iPhones
The small slit you see on the top edge of the iPhone 17 Pro and Pro Max is known as an antenna window. This subtle design element is made from a special radio-frequency-transparent material that allows high-band 5G (mmWave) signals to pass through without interference from the phone’s titanium frame.
Interestingly, this isn’t new. Older iPhone models that supported mmWave 5G — starting with the iPhone 12 Pro series — also included similar antenna windows, usually on the side frame. Apple has continued refining this design over the years to make it more seamless while still ensuring strong signal performance.
So, if you notice this small slit on your iPhone, know that it’s not a defect or random design choice — it’s a critical part of the 5G antenna system, ensuring fast and stable network speeds.
Bottom Line
So, that mysterious thing on the top edge of your iPhone 17 Pro or Pro Max isn’t a secret button or hidden sensor — it’s an antenna window that ensures your phone can deliver ultra-fast 5G speeds. Knowing this clears up confusion and helps you understand the sleek design choices behind Apple’s flagship phones.
