The first device with a colour e-paper display has launched.

From Freestyle Audio, it's a waterproof MP3 player with the high contrast screen angled as ideal for use in bright, outdoor conditions.

Made by Qualcomm, like other e-paper displays, it needs no backlighting.

It consists of two layers of a reflective material, some wavelengths of light bounce off the first layer, some pass through and bounce off the second.

Interference between the two beams creates the colour, and electrostatic forces control the distance between the layers.

Although tiny in this product - and arguably niche - it offers interesting possibility for other devices that use e-paper, such as e-book readers.