Amazon has launched Prime Book Box, a new subscription service that will deliver handpicked children’s books every one, two or three months to kids ages zero to 12.

Rolling out first in the US, Book Box is available exclusively to Prime members for US$22.99 per box. Users can select their preferences based on age, reading ability and delivery frequency, and then titles are curated by Amazon Books editors. Depending on a child’s age, either two hardcover books or four baby board books will be delivered beginning later this year.

Available titles include A Sick Day for Amos McGee by Philip C. Stead, The Willoughbys by Lois Lowry and Walk Two Moons by Sharon Creech.

Amazon’s move to sell more physical books comes as US print book sales were up significantly in 2016 and in 2015. According to The NPD Group, hardcover books outperformed eBooks in 2016 for the first time in five years. The print sales surge is especially strong in children’s publishing, with US kids print book sales growing faster than the overall physical book market with a compound annual growth rate of 5.3% since 201, according to NPD.