Free shipping on a Specific Product

We want to give out free books that you can either add to your cart with no extra cost or just request one and we will ship it with no cost to the customer. I can not find a way to do this in the discounts tab without it switching to "orders over' or "any order" Is this something that is possible with square space? 

You could set the book weight to, just saying, 100KG and then create a weight-based shipping rate that is free if the weight is over 100KG