[crazygringo]

You need to have Prime, and it usually requires you to have 2-3 items in your cart.

But if they're items that would normally ship in 1-2 days, then it will provide a credits option if you have an Amazon Day (day of the week for combined deliveries) selected and that Amazon Day is at least 3 days in the future. It will also sometimes instead show a "no-rush shipping" option that is usually something like 5-7 days out, with credits.

I'm not going to lie, I almost always select it (even constantly changing my Amazon Day to be at least 3 days out from today), and I'm pretty sure I make back my Prime membership fee and then some. The credits are usually $1.50-$4.50 per shipment, expire after 3 months, and can only be used for digital purchases like Kindle and videos.