AT&T is using CES to unveil the nifty Asus Padfone X, a 5-inch Android smartphone that powers a 9-inch tablet when docked.

The smartphone and tablet both run Android KitKat 4.4 and support HD voice, VoLTE and LTE-Advanced technology like carrier aggregation. Promising “seamless transition,” the Padfone smartphone operates independently and pops up on the tablet screen as soon as its slotted into the dock on the back of the tablet.

AT&T and Asus are also promising strong battery performance from the device. On Asus’ website, the company touts the latest model’s 63 hours of extended talk time.

Last year, Asus launched both the Padfone Infinity and Padfone mini in Taiwan. The announcement of the Padfone X coming to AT&T marks the U.S. debut for the device.

AT&T will be the exclusive carrier for the device. AT&T and Asus have already partnered on devices like the MeMO Pad 10-inch LTE tablet and the VivoTab. The carrier promised to soon announce pricing details and a release date for the Padfone X.