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If you let Amazon do a digital 3D-scan of your body, you might get a $25 gift card… to Amazon.

An online form, spotted earlier Wednesday by Mashable, lets interested participants sign up for a body scanning study conducted by Amazon Body Labs. The image study aims to learn about "diversity among body shapes," according to the form, and is operating at two different locations in New York, Mashable reported.

Amazon didn't respond to a request for comment.

Participants have to schedule an appointment before June 30, and apparently can only do it once. Data collected during the 30-minute session is meant for internal product research and not marketing, according to the sign-up form.

The form says participants will be asked to change into "minimal form-fitting clothing," noting that bikinis are preferred for women, but form-fitting shorts and sports bras are also acceptable. A reporter for Mashable signed up for a body scanning session and was asked to sign a non-disclosure agreement to keep everything they experienced or learned during the study confidential.

This isn't the first time Amazon has been curious about the human form. The e-commerce giant last year invited people to join a body-scan study that aimed to track small changes in shape and size in people's bodies over a 20-week period, The Wall Street Journal reported. Participants were reportedly offered Amazon gift cards worth up to $250 for being a part of the study.

Originally published May 22 at 10:23 a.m. PT.

Update, 12:53 p.m. PT: Adds background on Amazon's earlier body scan project.