A growing number of shopping holidays have cropped up over the years, including tax-free weekends and free shipping days. Now, the popular online marketplace Amazon has announced its own holiday, called Prime Day, which will reportedly feature more deals than the site has had for Black Friday in years past. Amazon sellers, although not fulfilling or providing customer service for Amazon Prime Day, will need to be prepared to handle peak order volume by ensuring inventory is available at FBA warehouses.

Amazon is throwing Prime Day to celebrate the company’s 20th anniversary as well as Prime subscribers, which Multichannel Merchant reported to be close to 50 million globally. The event could also help Amazon test the limits of the Prime service’s features during peak business days, which could be beneficial stress-testing ahead of the 2015 holiday season. Finally, the event itself may spur more signups for the service as well.

Prime Day is slated for July 15, with thousands of Lightning Deals and Deals of the Day, all shipping with unlimited two-day delivery, in accordance with the Prime program.

“Prime members can find deals on products across categories including electronics, toys, video games, movies, clothing, patio, lawn and garden, sports and outdoor items and more,” said Amazon’s announcement. “Members will enjoy deals on items perfect for summer adventures, their to-do list, family road trips, back to school supplies and everyday essentials. Prime members can shop on any device, including smartphones and tablets, and enjoy deals anytime and anywhere.”

Internet Retailer reported last month that Amazon may make more marketplace sellers’ products Prime-eligible, so if Prime Day becomes a recurring sales day, it could be an event for retailers to consider.