Apple will launch its newest smartphones exactly a year after their predecessors.

The iPhone 6S and iPhone 6S Plus will launch at an event on September 6 in San Fransisco, after a teaser invite was sent out with the words ‘Hey Siri, give us a hint’.

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The launch will be held exactly 12 months after the company revealed the iPhone 6 and iPhone 6 Plus, which became Apple’s “best selling devices ever”, CNET reported.

The iPhones reportedly make up more than two-thirds of the company’s revenue.

Although Apple is yet to discuss rumours around the new device, analysts have predicted the phone may not do as well as its predecessors. Rumours of diminished battery power and increased price may put off consumers, The Week reported.

“Apple’s next-generation smartphone, likely to be called either the iPhone 6S or iPhone 7, will be built from a high-grade aluminium alloy to prevent it bending in users’ pockets – and which will also add significantly to the cost of building the device,” the website reported.

“As a result, Apple will either have to charge more for the new iPhone, risking a dip in sales, or absorb the additional cost itself, denting its profit margin.”

Other rumours include the sophisticated screen feature Force Touch, which can differentiate between pressure applied to the screen, and more colour options – including Rose Gold.