The device come in two models - the HTC U Ultra and U Play - with a 5.7-inch and 5.2-inch screen respectively. The larger device also has a miniature second screen which can display important messages and notifications, by learning what contacts you communicate with regularly. The phones follow Apple's controversial decision last year to remove the headphone jack, instead connecting via Bluetooth or wired USB-C headphones. The smart features in the phone reflect how manufacturers have sought to make their devices more useful in an increasingly competitive market. Google added an artificial intelligence assistant to its new Pixel phone last year and Apple has sought to boost the capabilities of Siri.