> For the complete documentation index, see [llms.txt](https://zootopia-finance.gitbook.io/zootopia-finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://zootopia-finance.gitbook.io/zootopia-finance/citizens-passport/upgrade-and-synthesis.md).

# Upgrade & Synthesis

## Why upgrade or synthesize new NFT Cards

Zootopia provides 8 card slots for each user. Within the limited card slots, you can maximize your income by synthesizing or upgrading cards.

## Card Upgrade

{% content-ref url="/pages/zq3Qm6fn6vKAmYZ6cwJL" %}
[NFT Cards Overview](/zootopia-finance/citizens-passport/nft-cards-overview.md)
{% endcontent-ref %}

## Card Synthesize

Each character card in the GamePad game has its own different attributes and categories. By synthesizing different types of cards, combat effectiveness can be greatly improved.

This block of content will be available after the GamePad goes online, stay tuned.