Amazon’s (AMZN) blockbuster annual sale for its members has changed the way people shop, and made other companies scramble to try to cash in on the tech giant’s success.

Prime Day, which will occur on July 15-16 for a full 48 hours this year, pulled in an estimated $4.19 billion last year, according to Internet Retailer, a huge jump from over $2 billion in 2017. Now, increasingly more companies are attempting to grab their own slice of the pie.

On Thursday, Amazon rolled out a full menu of the deals consumers can expect to see, like big-screen TVs, mattresses, home goods and outdoor firepits. Analysts are already forecasting that the retailer will pull in big numbers.

The event is “essentially Cyber Monday meets Black Friday meets Boxing Day in the middle of July,” according to Sara Skirboll, a shopping and trends expert at the coupon company RetailMeNot.

While the bulk of deals will appear over the 15th and 16th, Prime Day has already begun to kick off. Prime members will be able to access early bird deals as early as Saturday, and bargains have also begun to spring up on Amazon's website.

Prime members can get up to 30% off on back-to-school and off-to-college items. Women’s activewear and Cuisinart cookware are also currently featured on the site, with deals rolling in at up to 50% off.

The most important week of back-to-school

RetailMeNot notes that Prime Day is the “official kick off to back-to-school shopping season,” one of the retail industry’s biggest seasons. A whopping 84% of retailers surveyed by RetailMeNot said they consider Prime Day to be the most important week of the entire back to school season.

The firm predicts that 250 retailers will take part in Prime Day deals, up from 194 in 2018. Last year, 11 of the top 20 products sold on Prime Day were actually manufactured by Amazon itself, along with four of the top five, according to figures from 1010data, which provides analytical intelligence and market data on consumer companies.

Fareeha Ali, director of research strategy at Internet Retailer, told Yahoo Finance in an email that Prime Day “will be bigger this year because it’s 12 hours longer than last year’s event.”

She added that “it will be held in 18 countries this year (one more than last year) and we have heard from sellers and other industry experts that more brands are offering Prime Day deals this year than past events.”

‘Tech was king’

Last year, Amazon’s Alexa-enabled Echo was a particularly big hit, and may be again this year as a streaming boom feeds interest in smart speakers.

“Tech was king,” said Matt Pace, a senior director at 1010data. “Prime Day deals were wide-ranging, but tech products, as in years past, carried the day largely thanks to American consumers’ insatiable appetite for the latest and greatest.”