Apple’s first foldable iPhone was apparently supposed to launch with a smaller Apple Pencil designed specifically for the device, but technical problems forced the company to abandon the accessory before it reached mass production.

According to Bloomberg’s Mark Gurman, Apple had been developing a shorter version of the Apple Pencil for the iPhone Duo. The stylus was intended to better suit the foldable iPhone’s smaller dimensions and was designed to attach magnetically to the side of the device. Apple ultimately scrapped the project after running into technical issues ahead of mass production.

The decision helps explain why Apple’s announcement of Apple Pencil support for the iPhone Duo was somewhat unusual. Rather than introducing a new accessory alongside the foldable phone, Apple said the Duo would eventually support the existing Apple Pencil with USB-C.

That support is not available at launch, either. Apple says the iPhone Duo will gain USB-C Apple Pencil support later this year, allowing users to take notes, sketch and mark up documents on both the inner and outer displays.

The original plan appears to have been considerably more tailored to the Duo. A shorter Pencil could have been carried directly with the foldable phone, with the magnetic attachment providing a natural way to keep the stylus with the device. Gurman had previously reported that Apple was working on a smaller Pencil that would attach magnetically to the side of the foldable iPhone.

But Apple ran into technical problems as the accessory approached mass production. It isn’t clear from the report whether those problems were primarily related to the Pencil itself, its magnetic attachment and charging system, or the interaction between the accessory and the Duo’s foldable hardware.

With the dedicated Pencil gone, Apple appears to have pivoted to an existing product rather than delay the broader stylus functionality. The USB-C Apple Pencil is already designed for iPad and does not require magnetic charging, making it a simpler option for the Duo.

There is one notable limitation. The iPhone Duo will support the USB-C Apple Pencil, but not the Apple Pencil Pro. Apple’s Pro stylus relies on magnetic charging and additional hardware features that the Duo does not support.

The USB-C Pencil also lacks several of the features found on the Pro model, including pressure sensitivity, double-tap controls, barrel roll, haptic feedback and Find My. It does support tilt sensitivity, making it suitable for basic writing, sketching and markup.

Apple’s decision to support an existing Pencil still makes the iPhone Duo the first iPhone capable of using Apple Pencil. But the delayed software support means buyers won’t get that capability when the foldable arrives.

The iPhone Duo is scheduled to go on sale October 23, with preorders beginning October 16. Apple says USB-C Apple Pencil support will arrive later in 2026.

So, in a slightly strange turn of events, Apple’s first Pencil-compatible iPhone won’t launch with the Pencil Apple originally designed for it. The shorter, Duo-specific stylus apparently got close enough to mass production for Apple to change course, leaving the regular USB-C Apple Pencil as the fallback option.