The Amazon Kindle is a series of e-book readers now in its fourth generation. Amazon Kindle eReaders enable users to shop for, download, browse, and read e-books, newspapers, magazines, blogs, and other digital media via wireless networking. The hardware platform, developed by Amazon.com subsidiary Lab126, began as a single device and now comprises a range of devices most using an E Ink electronic paper display capable of rendering 16 shades of gray to simulate reading on paper while minimizing power consumption. The Kindle name was devised by branding consultant Michael Cronan who was asked by Lab 126 to name the product. Cronan and partner Karin Hibma suggested Kindle. Etymologically, the word kindle relates to candle and they felt this was an apt metaphor for reading and intellectual excitement. Kindle hardware has evolved from the original Kindle introduced in 2007 and a Kindle DX line (with a larger screen) introduced in 2009. Announced in September 2011, the range now includes devices with keyboards (Kindle Keyboard), devices with touch sensitive screens (Kindle Touch), a tablet computer with a reader app and a color display (Kindle Fire) and a low-priced model with an on-screen keyboard (Kindle). Amazon has also introduced Kindle software for use on various devices and platforms, including Microsoft Windows, iOS, BlackBerry, Mac OS X (10.5 or later, Intel processor only), Android, webOS, and Windows Phone. Amazon also has a "cloud" reader to allow users to read, and purchase, Kindle books from a web browser. Content for the Kindle can be purchased online and downloaded wirelessly in some countries, using either standard Wi-Fi or Amazon's 3G "Whispernet" network. Whispernet is accessible without any monthly fee or wireless subscription, although fees can be incurred for the delivery of periodicals and other content when roaming internationally beyond the customer's home country. Through a service called "Whispersync," customers can synchronize reading progress, bookmarks and other information across Kindle hardware devices and other mobile devices. In the last three months of 2010, Amazon announced that in the United States, their amazon kindle 2 review sales had surpassed sales of paperback books for the first time.