If you've ever ordered from Amazon, you know that anything over $25 will ship for free on the "Super Saver" option, or you can also use Amazon Prime and get almost everything shipped to you within 2 days. Obviously, the heavier the object, the more expensive it is to ship; so what's Amazon's limit for item weights?
Based on their guidelines, the heaviest thing with Super Saver Shipping is a six-foot-tall Fire Safe. The Cannon Safe CO54 Commander Series Premium 90 Minute Fire Safe will hold 48 guns, has 13 locking bolts and costs almost $3500. How much does it weigh? 1,509 pounds!
The shipping company says that it usually charges $700 to ship the safe, so Amazon is taking quite a hit in offering the free shipping for this item. Why do they do it? Costumer satisfaction. Amazon knows that even if they take a hit on some items, the math adds up in the end, and they get a lot of happy costumers in return.