PulseOn wrist band uses Bluetooth Smart (LE / 4.0) with iOS mobile devices. Thus supported models are iPhone 4S and newer and iPad 3rd generation and newer.
Please see complete list below.

Supported iOS devices (Bluetooth Smart)
iPhone 4S
iPhone 5
iPhone 5C
iPhone 5S
iPhone 6
iPhone 6 Plus

iPad (3rd generation)
iPad (4th generation)
iPad Air
iPad Air 2

iPad Mini (1st generation)
iPad Mini 2
iPad Mini 3

Not supported
iPhone (1st generation)
iPhone 3G
iPhone 3GS
iPhone 4

iPad (1st generation)
iPad 2

iPod Touch 1st, 2nd, 3rd & 4th generation

iPod Touch 5th generation uses Bluetooth Smart, but currently we do not guarantee functionality as we have not tested enough.

Other iPod models not supported