Amazon is sending out free samples, tailor-made to users’ tastes with the help of their purchasing history, Axios reported earlier today. It’s unclear how long the company has been piloting this program, but it could become a larger part of its overall advertising strategy.

The samples are part of a partnership between Amazon and select brands that allows the brands to send users free samples, hoping they will spur further purchases. The product sampling website went up in December, and Axios pointed out a few social media posts from users who received samples in the mail dating as far back as August of last year. Information on the program is sparse, but the sampling page does explain that it’s free to participate and users can opt out if they would like. It appears that all users are automatically opted in.

“Amazon helps you discover products you might love by sending you FREE samples from new and established brands,” the website says. “It’s like Amazon’s product recommendations, but real, so you can try, smell, feel, and taste the latest products.”

As of right now, the program’s website only lists samples of products that consumers purchase repeatedly like dog food, makeup, toiletries and coffee. But it doesn’t look like the program will fade away any time soon. Over the summer, Amazon posted a job listing, seeking a senior-level person for its “Targeted Sampling” team.

Despite seeming delightful up front, this move could pose serious questions as it pertains to data privacy, especially in a year where regulation at the federal level is likely imminent. Amazon is uniquely poised to deliver targeted samples, since it already has customers’ addresses and extensive data on their purchasing habits.

Amazon declined to comment.

Updated 1/8/19 at 3:27 p.m. EST: Updated to add that Amazon declined to comment.