iPhone 6
iPhone 6 in Sam Beckett's concept video Screenshot from YouTube Video

Most of the iPhone 6 killer features on its rumoured September 19 release date remain subject for debate but three have emerged this week as strong candidates for confirmation, thanks to freshly leaked out information.

Bendable sapphire display at 4.7-inch

From the usually reliable Apple-dedicated blog site 9to5Mac, it appears that the next iPhone will benefit from extra-durability and that's because of a sapphire-made display that in a YouTube clip was shown with impressive durability.

While it is suggested that the same material will specifically grace the 5.5-inch iPhone 6 variant, the particular screen size is yet to be confirmed by Apple.

It is the 4.7-inch variant that seems to be approaching the brink of reality as shown in a new NowhereElse.fr video that BGR has picked up. In the video, the supposed iPhone 6 front panel is seen with a tape measure that diagonally runs over the screen.

And the measurement clearly reads: 4.7 inches.

Wi-Fi calling on iOS 8

Another feature that Apple fans will surely enjoy is Wi-Fi calling that according to Apple Insider is a new option activated by the iPhone maker for beta 3 of iOS 8. So far, two telcos have confirmed that the more stable and crystal-clear call service will be fully supported namely Rogers of Canada and T-Mobile of the United States.

It is understood too that the feature is already in usable state even in beta build, which points to the likelihood that the iPhone 6 with the official iOS 8 version will offer Wi-Fi calling, at least in select markets. One sure-fire benefit of the service, according to experts, is the elimination of drop calls - that is if users are within the signal range of a wireless router.

Maximum of 1900mAh battery rating

And lastly coming from Business Insider, the battery kit that is packed with the iPhone 5S replacement will come with a rating of 1900mAh, tops. Apple opted for the not too earth-shaking power juice numbers in order to deliver a super-slim iPhone 6 build profile.

But does this mean that the next iPhone will log in fewer operating hours compared to its rival Android flagships? Not necessarily, said Business Insider, explaining that expected tweaks packed with iOS 8 and the more energy-efficient A8 chip will likely extend the iPhone 6 battery life despite its jumbo-size screen and high-end components.

It is possible too, MacRumors said in a report, that the upcoming iPhone, like its predecessor, will have a co-processor that is similar to the M7 chip in iPhone 5S. In such case, the main CPU will be freed up from some processing tasks thus lessening bits of pressure from the on-board battery.

All these exciting features will be let out of the box come the iPhone 6 release date on September 19, which many analysts believe will be a simultaneous rollout for the 4.7-inch and 5.5-inch models.