The Express is the company's smallest product and is built to stream 1080p HD content, while the Express+ is for older TVs and comes with a composite AV connection.
The Roku Premier and Premier+ both support 4K Ultra HD video, and will upscale 720p content to 4K on compatable televisions. The range also features a night-listening mode which claims to "adjust audio sounds to aintain volume consistency".
The Premier+ model also has HDR comparability and a MicroSD input for additional storage, as well as an Ethernet port.
The Roku Ultra
At the top of the range is the Roku Ultra which has all the features of the Premier+, while also being compatable with Dolby Digital and Digital Plus, and with an optical digital audio out port so you can connect it to a sound bar or AV system. The Ultra also has a USB port and a "lost remote finder" feature.
The Roku Ultra is priced at $130, and the range will be available for pre-order from today in the US. There's no word on UK pricing or availability as yet.