Sony announced today that starting January 22nd, the Xperia Z1S will be available from T-Mobile. The Z1S is a variant of the Xperia Z1, Sony's current flagship device that's been for sale in different parts of the world for the past few months. It features a 5-inch, 1080p display, Qualcomm Snapdragon 800 processor, 2GB of RAM, and Sony's 20.7-megapixel camera. Like its predecessor, the Xperia Z, the Z1S is also waterproof, though it can be submerged a bit deeper than the Z (up to 4.9 feet for up to 30 minutes) thanks to its higher IP58 rating.

The Z1S runs Android 4.3 Jelly Bean with Sony's custom interface and apps. It has a number of apps to take advantage of its high-powered camera, including a new "background defocus" app, which lets you simulate the blur effect of a large camera and bright lens with your phone.

Compared to the Xperia Z, which T-Mobile will continue to sell alongside the new phone, the Z1S is slightly larger and heavier. It also has a dedicated camera key, but retains the rectangular shape and large glass front and rear panels of the older phone. The edges have been softened and refined, however, making the Z1S more comfortable to hold than the Z. The new processor is also much more powerful — the Z1S is noticeably snappier and more responsive than the Z ever was.

The Z1S looks very similar to the international Z1, though its headphone jack has been moved to the center of the top edge. Internally, everything is the same, save for more internal storage (32GB vs. 16GB) and full support for T-Mobile's network.

T-Mobile will offer preorders for the Z1S through its online store starting on January 13th, while it will go on general sale on the 22nd. The carrier has an exclusive on the device, so as with the Xperia Z, it's not likely that other US carriers will sell it anytime soon. The Z1S will sell for zero down and $22 per month for 24 months as part of T-Mobile's financing plans or for $603 outright.