As Amazon workers in the U.S. prepare to leave their posts in protest of working conditions, they will be joined by employees across Europe striking during the company’s biggest shopping event of the year.

The protests from Amazon employees in Germany, the United Kingdom, Spain, and Poland coincide with Prime Day, a 48-hour sale named for the Prime membership that gives Amazon shoppers who pay an annual fee perks including free deliveries. The striking workers across Europe are calling for safer work conditions and better pay, and demonstrations in some countries are expected to span two days.