This snippet allows you to insert a shortcode in WooCommerce that will look for a custom post type field added to the WooCommerce Product post type and then evaluate the data within that field for related items that you may wish to highlight. Instead of an Upsell or Cross sell that may be set by category relationships, the Commonly Used With plugin lets you precisely define your relationships by the SKUs in your store.
To present the data to your customers, the plugins will evaluate the SKU data, identify the corresponding product titles, and then replace the input value (either a single SKU or a CSV of SKUs) at the point of the shortcode with linked product titles.