Which accessories actually fit the iPhone Duo?

If you own an iPhone Duo, you'll want to keep it insured and protected. You may also be asking which accessories actually fit the device.

Apple's new foldable measures 164.6 by 117.8 by 5.2 mm unfolded, and 84.1 by 117.8 by 11.3 mm folded, differing significantly from traditional iPhones. Apple provides manufacturers with a trove of dimensional drawings, which illustrate why older fitted accessories, particularly cases, will not fit.

Some accessories remain compatible. USB-C peripherals and most wireless chargers continue to work, but mechanical car mounts, most lens accessories, many screen protectors and cases will be incompatible.

What does fit? Apple's online store offers a curated collection of approved third-party accessories you know will be compatible, but it's expensive — even the company's infamous polishing cloth costs $9. But when looking to purchase new accessories, it's important to search for solutions built to match iPhone Duo's unique design in not only its size, but also its functionality.

The new dimensions are an opportunity for manufacturers to try new approaches with accessories. For example, ESR's vegan leather magnetic case protects the entire phone, including the hinge mechanism, and has a movable kickstand that doubles as a lens protector. Mous offers a thin aramid case manufactured using the same material used in body armor. While it lacks hinge protection, it adds just 1.7 mm to the 11.3 mm maximum thickness of the Duo. Spigen's cases use the iPhone's folding mechanism as a stand, while the Spigen Armor case offers much more robust protection.

Protection isn't just about the frame. Even if they fit, traditional tempered glass protectors will crack when you snap the phone shut. When purchasing screen protection for the iPhone Duo, you should seek flexible TPU (thermoplastic polyurethane) or PET (polyethylene terephthalate) film protectors designed for the foldable device. While less scratch-resistant than glass, these films can handle repeated folding and won't crack when snapped shut.

Apple promises a future software update to enable the USB-C Apple Pencil to work with iPhone Duo. Unlike the Pencil 2 or Pro, the USB-C model has its own independent charging and pairing facility using USB-C. Supporting the other models would have required the smartphone to host an additional high-power wireless charging coil capable of external-facing power exchange, which would have added to the device's thickness, cost and weight.

The iPhone Duo supports MagSafe and 25-watt fast charging using the inbound wireless charging magnetic coils built into the rear panel of the device, underneath the camera. This means that existing MagSafe and Qi2 chargers should generally work. It also means MagSafe accessories should work, but as they are designed for the more traditional iPhone dimensions, you may find they overlap the device when connected.

MagSafe batteries will charge your device, but because they are designed to snap onto a longer iPhone, they will also hang off the edges of the frame. Accessory makers must create new MagSafe wallets and batteries to fit the new design.

When it comes to car mounts, magnetic MagSafe or Qi2 models should generally work with the iPhone Duo. Mechanical mounts may also be compatible, depending on whether their grips can accommodate the phone's dimensions.