Amazon has a new program that is available for Prime Members that allows them to try samples of select products. When you purchase one of the sample boxes, you get a credit for the same amount that can be used on future purchases in that category. This essentially makes the box you just purchased Free after the credit.
So if you purchase the Women's Beauty Sample Box for $9.99, you will get a $9.99 credit for a future Beauty (category) purchase.
Other Sample boxes include Nutrition & Wellness Sample Box, Dog Food and Treat Sample Box, Luxury Skin Care Sample Box, and Women's Luxury Beauty Sample Box.