The arrival of third-party iPhone and Mac accessories on Amazon is as predictable as the rising sun. Apple products are extremely popular, and Apple accessories tend to be expensive. But not all iPhone and Mac accessories are endorsed by Apple, and that can be dangerous for you.

In some cases, that's okay; Apple's Made for iPhone (MFI) rules state that unauthorized, unpowered cases are acceptable. However, the company has exempted MagSafe from this rule. This means that if you develop something that uses MagSafe, you must participate in the MFI program.

But are these inexpensive accessories any good? MacRumors looked at the smattering of available options and came to some interesting conclusions. One surprise is that Apple's official accessories do not charge the iPhone at a maximum of 15 watts. This was nearly half of the total for both official and unofficial hardware.

This may be due to the way charging is measured, but it is also possible that Apple is planning future devices with MagSafe that may require a bit more power. Reducing power also means reducing heat, which is important in protecting the device.

Heat tends to be a big battery killer. The more heat generated by charging, the more likely it is that battery life will be shortened. This is one reason why Apple's MagSafe design snaps in precisely and is generally made with high-quality components. Proper wireless connectivity prevents excess heat dissipation and keeps iPhones cooler. Along with other Apple features such as intelligent charging cycles, this may help extend battery life.

If you've been eyeing other accessories, such as saving a few bucks on a MagSafe wallet, using a third-party design may end up costing you big; in a MacRumor video, host Dan Barbera demonstrates how weak the unofficial magnetic connection is and how easy it is to lose money and credit cards if you use a non-Apple design.

What route you take is up to you. Indeed, MacRumors' findings suggest that some of the materials are of lower quality but equal in performance and function as well as Apple products. Other accessories may be more frustrating than dangerous. But the phrase "cheap goods are cheap goods" certainly resonates here.