During the IFA 2015 event, Sony unveiled three new devices: its flagship Xperia Z5, the smaller Xperia Z5 Compact, and the phablet Xperia Z5 Premium. But according to a report from Price Pony, the lineup is not yet complete — the Xperia Z5 Ultra is expected to be released in March next year. 

According to the report, the reason for the delay is because Sony will be using the upcoming Qualcomm Snapdragon 820 processor, which hasn't hit the market yet. Equipping the Xperia Z5 Ultra with the Snapdragon 820 will make it faster and more powerful, especially with the phone's inclusion of 4 GB RAM. 

The Z5 Ultra is reportedly going to sport a large 6.44-inch Ultra HD Display. Due to the expected high use of energy to properly utilize its large display and processing capabilities, the phablet is said to be equipped with a powerful 4000 mAh battery. In comparison, the Xperia Z5 Premium, widely famous for being the first smartphone to feature a full 4k Ultra HD display, is fitted with a 3430 mAh battery.  

Price Pony reports that the Z5 Ultra may utilize the same cooling system Sony utilized for the Xperia Z5 Premium. Although the architecture of the Snapdragon 820 is less prone to overheating, the company may still feature the same cooling system to stay on the safe side. 

Also stated is that the phablet will feature a 23 MP rear camera. It isn't clear if this will be a basic HD camera similar to those found in previous Xperia flagship phones or if it will utilize newer features such as 3D video recording, enhanced auto-focusing or other possible additions. No information has been released regarding its front camera at this point.

Sony has neither confirmed nor denied the speculations regarding the phablet's release or specs.