The online retail giant's third annual Prime Day sale covers a day plus six hours more this year and has expanded to 13 countries. Inc. holds its third annual Prime Day, a 30-hour event that started Monday night and runs through Tuesday.

The summer sales event is for members of Amazon’s Prime loyalty program, for which consumers pay an annual or monthly fee for free expedited shipping, streaming video, streaming music and digital photo storage. The promotion draws mostly from the U.S., but the sale also is available to consumers in 12 other countries this year.

Amazon, No. 1 in the Internet Retailer 2017 Top 500, has about 85 million U.S. members of its Prime loyalty program as of the end of June, up 34.9% from 63 million the same time last year, according to securities research firm Consumer Intelligence Research Partners (CIRP). Amazon does not disclose how many consumers are Prime customers. CIRP’s data is extrapolated from a survey of 500 shoppers in the U.S. who bought something on Amazon from April-June.