> ## Documentation Index
> Fetch the complete documentation index at: https://order-limit.xrtotech.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Shopify collection limit: 3 units across products

> Share a three-unit allowance across a Shopify collection. Configure combined quantity and test mixed carts, collection membership and unrelated items.

Your promotion includes products A, B and C. Customers can mix them freely, but the collection total in a cart must not exceed 3 units.

## When to use this

Use this when several samples or promotional products share an allowance. It allows combinations without creating bundles or discounts.

## Before you begin

Create a promotional collection containing distinct products A, B and C, plus one product outside the collection.

## Settings

Open the app home page → **All quantity rules** → create a rule.

| Setting | Example value |
| - | - |
| Rule name | Promotion collection: combined maximum 3 |
| Rule type | Cart quantity limit |
| Maximum quantity | 3 |
| Calculation | Limit the combined cart quantity of applicable items |
| Scope | Collections: promotion collection |
| Timing | Cart interactions and checkout |

## Steps

1. Open **Apps** → **订单限购** in Shopify. From the app home page, open **所有数量规则** and click **创建规则**.
2. Enter the rule name and thresholds from the settings table. The name is for admin use only.
3. Under **规则应用于**, select the scope in the table. For selected products or collections, click **选择产品** or **选择产品系列** and confirm the selected names appear.
4. Set the timing from the table. Under **保存后的状态**, select **已启用** and click **创建并启用**. When editing an existing rule, click **保存并启用**.
5. Return to **数量限制** and turn on **开启数量规则**. Confirm **购物车与结账校验** is enabled, using **启用校验** if necessary.
6. Reopen the rule to confirm its thresholds, scope, customer conditions and active state were saved. Run the storefront tests below.

## Test your configuration

Each result describes this recipe only. Keep the product scope consistent and verify checkout; other active rules may still block the cart.

| Test | Expected result for this scenario |
| - | - |
| A × 1 + B × 2 | Allowed: 3 units |
| A × 2 + B × 2 | Blocked: 4 units |
| A × 3 + 5 units outside the collection | Allowed by this rule |
| No items from the collection | Outside this rule’s scope |

> [!TIP]
>
> Products added to this collection later also match. Use **Specific products** if you want a fixed list instead.

Compare calculation methods in [quantity limits](https://order-limit.xrtotech.com/en/features/quantity.md).

## If results differ

If A × 2 plus B × 2 passes, check that calculation is combined and both products belong to the selected collection.

Use [troubleshooting](https://order-limit.xrtotech.com/en/troubleshooting/rules-not-working.md) to investigate. Complete the [launch checklist](https://order-limit.xrtotech.com/en/getting-started/launch-checklist.md) before rolling out.


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