It’s common practice for a retail website to make (non-competing) product recommendations.
Today’s invention is a way for product labels to advertise other, complementary products.

A label on a coat might say “This is a great product but have you thought about something like this as well? www.webaddress.com/1234 ?” indicating a small range of boots or hats or bags.
The labels would also carry a cellphone-readable barcode so that such products could be reviewed and ordered whilst shopping in a bricks-and-mortar store.