InTENSity IF Combo II - Rechargeable TENS & Interferential (IF) Combo DeviceInTENSity IF Combo II Rechargeable TENS & Interferential (IF) Combo Device The InTENSity IF Combo II is among the latest in the line of InTENSity pain relief devices. This is the first full line of portable, combination electrotherapy devices to have preset programs by body part, and customizable programs in one device. These devices have the most innovative, up to date programs and waveforms available to provide easy to use, noninvasive pain relief.