Screengrab from Amazon Flex

A few months after opening its first facility in Colorado, Amazon is hiring a slew of drivers to use their own cars to deliver packages to Denver-area shoppers.

These Amazon Flex jobs, which tout payments of $18 to $25 per hour, are not full-time. Rather, these are part of the gig or sharing economy, and could supplement other gigs such as driving for Uber or Lyft, running errands for Favor users or delivering groceries for Instacart.

“Amazon Flex is up and running in the Denver area,” Ashley Robinson, an Amazon spokesperson, confirmed in an e-mail.

Flex drivers need a car and smartphone. They also must be 21 or older, pass a background check and have an Amazon account. There’s no mention of who pays for gas, insurance and repairs, though other reports of the Flex program indicate that those expenses are the responsibility of the driver.

According to its site, Amazon Flex drivers sign up for available hours on the mobile app. But drivers can’t choose specific neighborhoods or have a package preference.

Flex’s site says that people who deliver Prime Now packages — the one-hour delivery service — have “estimated earnings of $36-$50 per delivery block,” which includes tips, for two hours of work. According to Amazon’s Prime Now page, the one-hour delivery service is not yet available in Denver.

Regular Amazon.com deliveries have similar “estimated earnings” of $72 per block of about four hours of work.

“Compensation varies,” Robinson said. “However, on average, participants can earn up to $25 per hour or more.”

More details about the gig weren’t readily available. But other sites have written about what it’s like to work for Amazon Flex. TheRideShareGuy shared one driver’s experience in Seattle, where Amazon is headquartered. The driver reserved his availability the prior week and then headed to the pickup location for the packages. After delivering the package, he headed back to the pick up center to wait for another package. He was paid $18 per hour and collected enough tips to make it $21.60 per hour.

Amazon’s Aurora warehouse, which had 250 hourly employees on opening day in June, is still hiring workers at $13 an hour. Those jobs include medical coverage and weekly payments.