The version of Bluetooth running on your device depends on the iOS version. The iPhone 6s supports bluetooth version 4.2. Check out their specifications page here Apple iPhone 5 supports Bluetooth 4.0 that also has backward functionality meaning it can also run versions 3.0 and older. read more
The iPhone 5 uses Bluetooth 4.0 technology. This can connect to any Bluetooth 4.0 or lower device through Bluetooth. iPhone 5 - Technical Specifications. If you buy a Bluetooth 2.0 accessory, it may use less power on a Bluetooth 4.0 device. read more
The version of Bluetooth running on your device depends on the iOS version. The iPhone 6s supports bluetooth version 4.2.The iPhone 5 supports Bluetooth 4.0 that also has backward functionality meaning it can also run versions 3.0 and older. read more
Bluetooth 5.0 also promises twice the data transfer speed of the previous version. However, perhaps most excitingly, Bluetooth 5.0 has enough bandwidth to support two sets of wireless devices at the same time. read more