> For the complete documentation index, see [llms.txt](https://yung-pixels.gitbook.io/whitepaper/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yung-pixels.gitbook.io/whitepaper/technological-overview/erc-1155.md).

# ERC 1155

## Why we chose ERC-1155?

The ERC 721 is the most common standard for NFT, but it can cost a lot to buy more than one token.\
\
E.g.: Assuming 300 gwei and $3500/ETH, this table is the comparison of gas cost between 721 and 1155 with our smart contract:

| NUMBER OF YUNG PIXELS | USD MINT COST (ERC 721) | USD MINT COST (ERC 1155) |
| --------------------- | :---------------------: | :----------------------: |
| Buy 1                 |         $162.55         |          $61.14          |
| Buy 2                 |         $283.86         |          $61.14          |
| Buy 3                 |         $461.84         |          $61.14          |
| Buy 4                 |         $526.46         |          $61.14          |
| Buy 5                 |         $740.30         |          $61.14          |

This comparison show us that the mint cost of ERC-721 NFTs goes progressively higher as the number of Yung Pixels bought increases, and that doesn't happen with the 1155 standard. So we opted to utilize ERC-1155. This way, if someone wants to buy 1,000 YP, it will pay approximately $61.14 as gas cost, the same as someone that buys 1.

{% hint style="danger" %}
**Those numbers may not reflect the real-world values**, **but we guarantee that the gas cost will be the same independent of the number of Yung Pixels bought with the same gwei value.** 
{% endhint %}

Due to adoption of the ERC 1155 standard, every unrevealed and revealing Yung Pixels have a common ID that is the same for all the owners, but each owner can reveal their Yung Pixels in our website. This way, Chainlink's VRF will generate a unique revealed Yung Pixel! ERC 1155 came as an excellent tool to our project.

![Exemple of Unrevealed Yung Pixel (5 owners)](/files/Y4FcPN5kLZl4vlYktDSA)

**Safe, cheap, simple!**