The U.S. government website to order free, at-home coronavirus tests opened up for a second round of orders on Monday, the White House announced, allowing Americans to sign up for another four tests per household.

Already more than 270 million test kits have been shipped to households around the country as part of 68 million orders since the website launched on Jan. 18, according to the U.S. Postal Service.

The U.S. government has promised to purchase a total of one billion tests for free shipping around the country in the coming months, and the first round of tests became available on Jan. 18.

President Joe Biden shared a video message about the second round of tests on Twitter Monday afternoon.

“Today, I want you to know that if you’ve already ordered free tests, you can now order another round, shipped directly to your home and for free, so we’re prepared no matter what COVID-19 brings,” he said.

He encouraged Americans to go online to COVIDtests.gov to order.

Biden had announced in his State of the Union address last week that another round of free tests was coming.

The postal service said in a statement last week that it takes an average of 1.2 days to deliver a package of the free test kits once it enters the mailstream. 

USPS has hired thousands of temporary postal workers to package and ship the kits from more than 40 annex locations around the country.