How does AdNabu use Compare at price in Google Shopping Feed?

Google shopping feed app by AdNabu supports compare at price by Shopify to be added to the products

AdNabu uses compare at price in Shopify to create the sale price attribute in Google Shopping Feed.

You can add compare at price for the product in Shopify. Compare at price must be higher than the price.

If compare at price exists in Shopify, Google Shopping Feed will have two attributes:- Price and Sale Price. Compare at price will be mapped to price and price from Shopify will be mapped to sale price in Google Shopping Feed. 

If compare at price is not given, the price from Shopify will be directly mapped to price in Google Shopping Feed.