(Reuters) – Amazon.com Inc on Friday unveiled a subscription service that allows customers to read as much as they choose from its library of more than 600,000 e-books. Subscribers to the Kindle Unlimited service, which costs $9.99 per month, can read the e-books on Amazons Kindle reader or on any device that supports the Kindle app. Customers can choose from books including The Hunger Games, Life of Pi, and Diary of a Wimpy Kid. Subscribers also have access to thousands of audio books. Amazons service competes with others in the market including Oyster, which charges $9.95 per month for unlimited access to more than 500,000 titles.