FYI, others have probably seen already, but something new.
Been playing with different items and it looks like its offered with certain items as long as final checkout is over $20. Might be wrong though.
About FREE No-Rush Shipping - $20 Credit
This No-Rush credit expires on February 28, 2017. Terms and Conditions apply.
Choose FREE No-Rush Shipping and we'll automatically apply a $20 credit for any Amazon home service to your account once your order ships. To redeem your $20 credit, go to Amazon.com/services and add a service to your cart. We'll automatically apply the credit at checkout. Offer redemption requires customers to be in the U.S.
Add 2 to cart and checkout. you should see FREE No-Rush Shipping $20 Credit
OxiClean Versatile Stain Remover, 7.22 Lbs