Online retailer amazon.com said Kindle owners with an Amazon Prime membership will now get access to the company’s new digital book library service for free.

Kindle owners with the Prime membership can choose from thousands of books to borrow for free on a Kindle device, including more than 100 current and former New York Times bestsellers, as frequently as a book a month, the company said.

Amazon Prime costs $79 a year in the United States and gives members free two-day shipping, along with free access to almost 13,000 TV shows and movies from the company’s internet streaming service.

Reuters