Source: Phil Nickinson / Android Central (Image credit: Source: Phil Nickinson / Android Central)
The OnePlus X, meanwhile, offered flagship-tier performance in a compact chassis. Phones back in 2015 weren't massive by today's standards, but the large screen trend firmly took root and devices were becoming increasingly unwieldy. The glass back and compact form factor made the OnePlus X immediately stand out from other devices. Because of the limited storage, the OnePlus X was the only phone from the manufacturer to offer an SD card slot. Its diminutive size made it perfect for one-handed use, and to this day, the OnePlus X has a lot of fans. While the phone wasn't a huge success, it attracted a sizable following for its form factor. There were obviously a lot of compromises to get to that low retail figure: the phone lacked a fingerprint sensor, offered just 16GB of storage, there was no NFC, it was powered by an older Snapdragon 801 chipset, and had a Micro-USB port. The OnePlus X was the perfect compact phone, and we're long overdue a sequel. Debuting in October 2015 for just $249, it continues to be the most affordable phone launched by the company. The OnePlus X was an ambitious bet for the Chinese manufacturer as it set its sights on the mainstream market. Source: Andrew Martonik / Android Central (Image credit: Source: Andrew Martonik / Android Central) The feature was an instant hit, and has been a mainstay on all OnePlus phones that followed. The OnePlus 2 also introduced the Alert Slider, a dedicated hardware key that lets you quickly switch between various notification profiles. While the OnePlus 2 may not have been the first phone in the world with USB-C charging (that honor goes to the LeTV Le 1), but it was the first to make the standard available to a mainstream audience.
Remember, Samsung's flagship at the time - the Galaxy S6 series - had a Micro-USB charging port.
The OnePlus 2 was also the first OnePlus phone to feature a USB-C charging port, and that was a big deal at the time. The phone featured a metal mid-frame and had noticeably better build quality, and it came with a fingerprint sensor on the bottom bezel. The OnePlus 2 introduced USB-C charging, the Alert Slider, and much better build quality. OnePlus debuted five back covers with the device: Bamboo, Black Apricot, Kevlar, Rosewood, and Sandstone Black. It launched in July 2015 for $329, and had unique customization options in the form of StyleSwap back covers that let users switch out the back cover to a material of their liking.
The OnePlus One was a tough act to follow, but OnePlus introduced a laundry list of improvements to the OnePlus 2. Source: Apoorva Bhardwaj / Android Central (Image credit: Source: Apoorva Bhardwaj / Android Central)