When shipping is always free after an annual fee, who’s to say where Amazon Prime members will stop shopping? Sure, the company is betting that most members will be shipping smaller, everyday items — but what if you wanted to ship something super heavy, say, a 1,509-pound gun safe? Well, that would be free, too, even though it’d probably cost Amazon a tidy sum to ship.

MarketWatch delves into the wide world of products that qualify for free shipping in the online retailer’s Prime program, and found that there don’t seem to be a limit on the weight of items it’ll ship for free once you pay the $79 annual fee.

Since you can buy anything from a package of cotton underwear to the aforementioned incredibly heavy safe (which seems to be the weightiest item available for free shipping), a customer can easily make that $79 membership worth it with just one purchase.

So why would Amazon want to give its Prime members such free range? Exactly because it would seem there aren’t too many people in the market for a Cannon Safe CO54 Commander Series Premium 90 Minute Fire Safe (which can hold 48 guns and also protect your other things in need of protecting). If you can wait a few days for your safe, you don’t even need to be a Prime member to get free shipping.

It would seem to be a win-win — Amazon gets happy customers ordering up average items all year long with free shipping, and customers get free shipping all year long. As long as every member doesn’t start buying super heavy safes, treadmills or other bulky objects, that is.

Some analysts are skeptical though, noting that Amazon won’t discuss a lot of specifics about the economics behind its Prime program, even while reporting shipping losses in the most recent fiscal quarter. Why lose money when you could make a profit, if not for that pesky free shipping?

It’s somewhat of a mystery, but as CEO Jeff Bezos noted to AllThingsD in September (via MarketWatch):

“Despite what some have said from time to time, Amazon is a for-profit business. So, we looked at some numbers, and we believed that this would be a good program for customers and for Amazon.”

In other words, customers are probably going to stay happy with Amazon as long as that shipping stays free, which is in itself, its own profit. Now excuse me while I purchase 20 cases of 50-pound dumbbells, if those are even a thing.

The elephant in Amazon’s mail room: The retailer’s free-shipping policies extend to 1,000-pound items [MarketWatch]

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