From the product page:
Each door represents 1 set of unique Acrylic Mystery Dice! Every additional set ordered will be a different mystery dice set, meaning you can choose any combination of doors!
Every purchase also includes:
* 4x Digital map downloads
* 4x Rare digital D&D item downloads
* 1x Printable Character Sheet
The Tabletop Game Shop is a great family-run shop out of the US that specialises in acrylic and metal dice, and dice accessories. Their recent Black Friday sales were great, but they're still offering some good, cheap, high quality dice and a bonus bundle of digital DnD resources.
These are standard sets of 7 dice (D3, D4, D6, D8, D10, D12, D20) for your tabletop games (or some rad decorations!)
You can scroll to the bottom of the page for product reviews, and to see what some of the 20 different sets look like.