The viewer works by phone owners inserting their handset into a cardboard shell that contains optical lenses. With a supporting game or app running on the phone, the image on the screen is split into two halves.
By looking into the lenses, the images are combined into one immersive, 3D image. Many Cardboard apps also use a phone's gyroscope and accelerometer to let users look around the virtual world.
Previously the popular cardboard device was only available outside of the U.S. via third parties and promotional offers, but Google is now offering it direct to international customers via its online store.
The VR viewer is available in Canada for $20 each or $35 for a pair, 20 Euros each or 30 Euros for two in France and Germany, and £15 each or £25 a pair in the U.K.
Cardboard supports Apple's range of iPhones and has an interactive click button that works with all compatible handsets.
(Via The Verge.)