Apple's foldable smartphone, the iPhone Duo, has limited compatibility with existing iPhone accessories. Many USB-C peripherals and wireless chargers can still be used, but cases and screen protectors require dedicated products that match its folding design and changed size.

On Oct. 12 (local time), IT-focused media outlet Engadget reported that the iPhone Duo is designed with a different form factor from existing iPhones, and accessory compatibility varies widely by type. In particular, cases and screen protection products need to be chosen anew to reflect the foldable structure.

The iPhone Duo measures 164.6×117.8×5.2 mm when unfolded and 84.1×117.8×11.3 mm when folded. Its exterior differs significantly from bar-type iPhones, making it difficult to use standard cases as they are. Apple is providing detailed dimension drawings so accessory makers can design products.

Charging accessories are relatively compatible. Existing USB-C peripherals can continue to be used, and most existing MagSafe and Qi2 chargers also generally work through a magnetic coil for wireless charging placed under the rear camera. MagSafe accessories made to fit existing iPhone sizes may cover part of the device's edges. MagSafe battery packs can also charge it, but they may protrude beyond the device because they do not match the iPhone Duo's size.

Screen protectors require greater care in selection. Even if standard tempered-glass protectors fit, they can break during folding. Flexible films made of thermoplastic polyurethane (TPU) or polyethylene terephthalate (PET), designed to withstand repeated folding, are cited as an alternative.

Accessory makers are also rolling out products tailored to the iPhone Duo's structure. ESR highlighted a magnetic case made of vegan leather that covers the hinge, along with a kickstand that also serves as lens protection. Mous introduced a case using aramid fiber, also used in bulletproof vests, limiting added thickness to about 1.7 mm. Spigen unveiled a product that uses the foldable structure like a stand, while Armor Case focused on enhanced protection performance.

Apple Pencil support is also limited to some models. Apple plans to support use of the USB-C Apple Pencil on the iPhone Duo through a future software update. The Apple Pencil 2 and Apple Pencil Pro are excluded from supported models.

This is related to differences in charging methods. The USB-C Apple Pencil handles charging and pairing through its own USB-C connection, but supporting other models would require a separate wireless charging design that allows the device to deliver power to the pencil. Apple is reported to have judged that such a configuration could increase thickness, cost and weight.

Compatibility for car mounts depends on the mounting method. Magnetic mounts that use MagSafe or Qi2 can generally be used, but mechanical products that clamp the smartphone need to be checked to see whether they can accommodate the iPhone Duo's size.

Ultimately, the iPhone Duo is expected to create new demand in key protective goods markets such as cases and screen protectors, while largely maintaining existing compatibility for charging-related accessories. Apple's online store is also separately selecting and selling third-party accessories with confirmed compatibility.

iPhone Duo buyers do not need to replace existing accessories unconditionally, but they should check compatibility by product. In particular, screen protectors and cases need to be chosen by considering not only size, but also the folding structure and whether the hinge is protected.