Leaked images of the next iPhone are a staple in the months leading up to a launch, but according to a new report, the pictures of the iPhone 6 that have been popping up on the Web for months might not be the final design.

Japanese newspaper Nikkei reported Monday that the iPhone 6 mockups available on the Internet are still just working models, stating that some “key details are omitted.” Primarily, Nikkei says that the white stripes seen on the reverse side of the smartphone are just indicators for manufacturers, showing them where to replace aluminum with glass.

Currently, the iPhone 6 design differs from the iPhone 5s in several ways. One of the more striking differences is the lack of glass on the rear of the phone. The iPhone 5/5s has glass sections on the top and bottom of the back plate, whereas the iPhone 6 mockups are full metal.

Also notable is the lack of an Apple insignia, but that could be just because these are working models. Nikkei states that the logo will be a physical cutout, and some photos of alleged iPhone 6 rear shells support Nikkei’s claims, but mockups vary dramatically in the beginning of the production period. The iPhone 5s has a polished engraved logo of the Cupertino, Calif.-based tech giant. 

Also missing from the current mockups, according to Nikkei, is the curved glass display that some sources have said will transition seamlessly into the aluminum case. Nikkei isn’t the only newspaper reporting that the iPhone 6 will have a curved glass display. Bloomberg and Mac Otakara have both reported similar findings.

The iPhone 6 is expected to launch in a few months, with an announcement on Sept. 9 and the official launch on Sept. 19. That's the third Friday of the month, which would jibe with the launch dates of Apple's last three iPhones.

The iPhone 6 is said to run a 2.6GHz A8 processor and have 2GB of RAM. Purportedly, Apple will release two sizes of the iPhone 6, a 4.7-inch model and a 5.5-inch model. Some sources say both versions will launch on the same day, while others push the larger model’s release to early 2015.