# Scan Serial Numbers at Shopify POS

> Add the SKUSavvy Scan serials tile to Shopify POS and scan serial numbers at checkout, so each sale removes exactly that unit from stock.

## Scan Serial Numbers at Shopify POS
To sell a serialized unit at Shopify POS, you scan its serial number with the **Scan serials** tile. The serial goes onto the cart line, so when the order syncs SKUSavvy removes exactly that unit from stock instead of any unit of the product.
Before you start: the store must be connected through the SKUSavvy app from the Shopify App Store, and serialized inventory must be on in SKUSavvy. Stores connected through their own custom app can't add the tile.
## Add the Scan Serials Tile
You add the tile once per smart grid template in Shopify admin. Every POS device that uses that template then shows it.
1. Open the **POS editor** in Shopify admin. You can also go to **Sales channels** > **Point of Sale** and edit the POS app.
1. Expand the page you want the tile on, usually **Page 1**, so the tile sits where cashiers already look.
1. Click **Add tile**.
1. Click **Embedded Apps**, because the tile comes from the SKUSavvy app.
1. Select **SKUSavvy**.
1. Select **Scan serials** (POS UI extension), then click **Save** to publish the tile to your POS devices.
![Shopify POS editor with Add tile under Page 1 and the Add tile menu open on Embedded Apps](https://res.cloudinary.com/deoyetsee/image/upload/v1791351750/75c5da566931f9339fa3a3fa44393d06.png)
![Embedded Apps menu in the Shopify POS editor with SKUSavvy selected](https://res.cloudinary.com/deoyetsee/image/upload/v1791351751/4d50ca0de618c727e053882be59d26e0.png)
After you save, the **Scan serials** tile appears on the POS home screen of every device that uses the template.
![Shopify POS home screen on an iPad with the Scan serials tile added to the smart grid](https://res.cloudinary.com/deoyetsee/image/upload/v1791351751/1c13780175b6826b0d6b735347cb3304.png)
In SKUSavvy, **Company** > **Shopify** links straight to the POS editor for each store and lists the same steps.
#### If the tile doesn't appear on a device
Shopify can take a few hours to deliver a new or updated app tile to POS devices, even after it shows in the POS editor. To make the device check again, sign out of the store in the POS app and sign back in. Sign out of the store itself, not just the staff PIN screen, so POS reloads its apps.
If the tile still doesn't appear, check that the device's Location uses the smart grid template you edited, since each Location can use a different template.
## Scan a Serial Number at Checkout
1. Tap **Scan serials** on the POS home screen. With a connected or built-in scanner, the tile shows **Listening for scans**. On a device that only has a camera, the camera opens on its own.
1. Scan the serial number. To use the camera at any time, tap **Scan with camera**.
1. Check the **Scanned** list in the tile: an **Added** badge means the unit is on its own cart line with its serial.
1. Close the tile and check out as usual.
SKUSavvy looks up a serial number first. If nothing matches, it checks your product barcodes, so a scanned product barcode adds the item without a serial. Bin barcodes never match.
Each serial gets its own cart line, so two units of the same product show as two lines. This keeps every serial tied to exactly one unit when the order syncs.
## What Happens After the Sale
POS orders reach SKUSavvy already fulfilled. When the order syncs, SKUSavvy finds the stock with that serial number in the Warehouse mapped to the POS Location and removes it. The serial match takes priority over the POS bin, so the unit you scanned is the unit that leaves stock.
To confirm it worked, search the serial number in your inventory after the sale. The unit no longer appears. Units sold without a scanned serial follow the normal POS rules in the [POS orders guide](/docs/guides/orders/pos).
## Scan Messages
- **In cart**: you scanned a serial that is on another cart line. A serial can only be sold once, so the second scan is ignored.
- **Not found**: the value isn't a serial or product barcode for this store, or that serial is already sold. Check the item is serialized in SKUSavvy and received into stock.
- **Other location**: the serial is in stock at a different Warehouse than the POS Location. A serial can only be sold where it's held, so SKUSavvy removes exactly that unit. Move the unit in SKUSavvy first, or sell it from its own Location.
- **Failed** with **This POS location has no SKUSavvy warehouse**: the POS Location isn't synced to a SKUSavvy Warehouse. Check the Location's mapping in **Company** > **Shopify**.
- **Failed** with **Store is not connected to SKUSavvy**: the Shopify store isn't linked to a SKUSavvy account. Connect it in **Company** > **Shopify**, then scan again.
- **Failed** with **Lookup failed, scan again**: SKUSavvy didn't respond. Scan the item again; if it keeps failing, check the device's internet connection.
- **Not added**: the cashier closed Shopify's out-of-stock prompt, so POS didn't add the item.
Every lookup goes to SKUSavvy, so the tile needs an internet connection. While the device is offline, the tile shows **Offline** and scans aren't added.