> ## Documentation Index
> Fetch the complete documentation index at: https://docs.supercycle.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Link new and circular products
> Add a switcher between a product sold new and its circular twin on the same product page
This snippet goes in a **Custom Liquid** block in the theme editor, so it works in any Online Store 2.0 theme. It styles itself with the Methods app block's classes, so the Supercycle Engine app embed needs to be on.
You can sell a product new and offer it through circular methods such as resale, rental, or subscription from the same product page. To do that, create 2 Shopify products, one for the new product and one for the circular methods, and add a switcher that links them. Supercycle finds the pair by a suffix on the product handle.
***
## How it works
The switcher relies on a naming convention for product handles:
* **Base product.** The product sold new, for example `t-shirt`.
* **Linked product.** The product with circular methods in Supercycle, with a suffix on the same handle, for example `t-shirt-circular`.
When a customer views either product, the block looks up the other by handle and shows a switcher between the new and circular versions. It only renders when both products exist, so a product without a twin shows nothing.
You need both products before you start: a Shopify product for the new item, and a separate Shopify product set up in Supercycle with the suffix on its handle.
***
## Add the switcher
On **[Themes](https://admin.shopify.com/themes)**, select **Customize** on your theme, then open a product page from the page selector at the top.
In the left sidebar, select **Add block** in the product information section, then **Custom Liquid**.
Paste this into the block's **Liquid code** field.
```liquid Custom Liquid block theme={null}
{%- comment -%} Configurable variables {%- endcomment -%}
{% assign new_label = 'New' %}
{% assign linked_label = 'Resale' %}
{% assign linked_suffix = '-resale' %}
{%- comment -%}
Work out base / linked handles
{%- endcomment -%}
{% assign current = product.handle %}
{% assign base = current | replace: linked_suffix, '' %}
{% assign is_linked = false %}
{% if base != current %}
{% assign is_linked = true %}
{% endif %}
{% assign linked = base | append: linked_suffix %}
{%- comment -%} Look up products {%- endcomment -%}
{% assign base_product = all_products[base] %}
{% assign linked_product = all_products[linked] %}
{%- comment -%}
Only show switcher when:
- linked_suffix is not blank
- base product exists
- linked product exists and is a real product
{%- endcomment -%}
{% if linked_suffix != blank and base_product and linked_product and linked_product.title != blank %}
{%- comment -%} Base option (no suffix) {%- endcomment -%}
{% endif %}
```
Change the three assignments at the top to match your labels and handle suffix.
```liquid Variables theme={null}
{% assign new_label = 'New' %}
{% assign linked_label = 'Resale' %}
{% assign linked_suffix = '-circular' %}
```
| Variable | Description | Examples |
| --------------- | ---------------------------------------------------------------- | ------------------------------------------------- |
| `new_label` | Label for the new product option | `New`, `Buy New` |
| `linked_label` | Label for the Supercycle product option | `Resale`, `Rental`, `Circular`, `Buy refurbished` |
| `linked_suffix` | Suffix on the base handle that identifies the Supercycle product | `-circular`, `-resale`, `-rental` |
Select **Save**, then open both products on the storefront. The switcher uses the same classes as the Methods app block, so it takes the block's styling.
The switcher only appears when both the base product and the linked Supercycle product exist. If either is missing, nothing renders.
