(Pocket-lint) - After making its flagship phone available to buy without needing an invite, OnePlus has now opened up orders for the OnePlus X too.

"As we continue to move our business forward we will never stop looking for exciting new ways to reinvent ourselves. That's why we're excited to announce that, as of today, the OnePlus X is completely free," the company says in a blog posting.

The OnePlus X costs £199 to UK buyers, with free shipping. It is available in onyx, champagne and ceramic colour themes, and can be bought from the OnePlus online store.

A protective case adds up to an extra £19.99 to the bill.

The OnePlus X has a 2.3GHz quad-core Qualcomm Snapdragon 801 processor, Adreno 330 graphics, and 3GB of RAM.

READ: OnePlus X review

It comes with 16GB of storage, with a microSD card slot capable of expanding that by a further 128GB.

The screen is a 5-inch Full HD OLED display, while the rear-facing camera is 13-megapixels. There's an 8-megapixel camera on the front. It is capable of recording video in 1080p.

The phone is compatible with UK 4G networks and runs on OnePlus' own operating system, OxygenOS, which is based on Android 5.1.1.

The OnePlus X was available without an invite for a brief period during the Black Friday week, but now it's available to all.

Writing by Rik Henderson.