Amazon is selling its own COVID-19 test kit directly to customers. Results from the test will appear on an Amazon diagnostics website that was originally designed for use by Amazon employees. The test’s public availability was first reported by Stat News.

The test is on sale for $39.99 and has one-day shipping through Prime in some areas of the US.

To use the test, a patient swabs their own nose at home and places it in a box with a prepaid shipping return label. The swabs are then sent to a centralized lab. Amazon got the Food and Drug Administration’s sign-off on its COVID-19 test kit in March. At the time, it planned to use the test for its onsite employee testing program.

At-home medical testing got a new burst of attention over the past year, as companies raced to deliver COVID-19 tests that people could take easily without a trip to the doctor’s office. Experts think it’ll supercharge efforts to bring other types of at-home tests, like flu tests, to the market more quickly.

Amazon also offers a COVID-19 testing kit made by the genomics company DxTerity and a rapid 10-minute testing kit made by Quidel. They sell for $99 and $24.95, respectively.

The in-house COVID-19 test kit is the latest in Amazon’s expansion into healthcare. The company started offering its telehealth and at-home healthcare program to other employers in March. It’s also offering six-month prescriptions for common medications starting at $6 through its Amazon Pharmacy program.