It seems that Apple has upgraded some of its devices from bluetooth 4.0 to bluetooth 4.2 without notice. The changes in specifications can be found on the product page on Apple’s website.
AppleInsider discovered that the specifications for the iPhone 6, iPhone 6 Plus and the iPad Air 2 have been changed. Where it was previously reported that the iOS devices have support for bluetooth 4.0, it is now version 4.2. It is unclear whether this is due to a software update or whether Apple has quietly built in new chips, so it is not known whether previously sold devices also have Bluetooth 4.2. It is clear that the product number of the devices has not changed. Apple has not yet responded to the report.
Compared to bluetooth 4.0, version 4.2 offers more speed for transferring files and better security features. Newer devices from Apple, such as the iPhone 6s and iPhone 6s Plus, already have support for Bluetooth 4.2.