# Option 4: Buy Sentry Key via Node License Contract on Arbiscan

1. Go to the Node License contract on Arbiscan:

{% embed url="<https://arbiscan.io/address/0xbc14d8563b248B79689ECbc43bBa53290e0b6b66#readProxyContract>" %}

2. Scroll down to the "17. price" function at the bottom of the page.
3. Enter the number of Keys you want to purchase to get the price.

<figure><img src="https://content.gitbook.com/content/neke8a6D4Ybg9dkRA2GD/blobs/hIjQbWtMdMCBphXmvpUU/image.png" alt=""><figcaption></figcaption></figure>

3. Grab the number next to uint256. In this example, copy the value 220986939450000000.
4. Enter the number into the "Wei" field of the converter tool:

{% embed url="<https://eth-converter.com/>" %}

5. Copy the value in the Ether field. In this example, 0.22098693945.

<figure><img src="https://content.gitbook.com/content/neke8a6D4Ybg9dkRA2GD/blobs/JEWbsuxWVjtobLhBwHht/image.png" alt=""><figcaption></figcaption></figure>

6. Go back to the Node License contract on Arbiscan: <https://arbiscan.io/address/0xbc14d8563b248B79689ECbc43bBa53290e0b6b66#writeProxyContract>
7. Connect your Web3 wallet.

<figure><img src="https://content.gitbook.com/content/neke8a6D4Ybg9dkRA2GD/blobs/VWIpRY6eOCMH2GWg0wqS/image.png" alt=""><figcaption></figcaption></figure>

8. Click "5. mint"

<figure><img src="https://content.gitbook.com/content/neke8a6D4Ybg9dkRA2GD/blobs/Qc250YvflMC4WCLsjYYJ/image.png" alt=""><figcaption></figcaption></figure>

9. Paste in the value from Step 6 into the "mint" field.
10. Enter the quantity of Keys you would like to purchase in the "\_amount (uint256)" field. Use the same amount you entered in Step 3.
11. Click Write.
12. Approve the transaction in your wallet.