This expression pedal is specifically designed for use with the Line 6 Helix units.
I have the rack version of the Helix and the separate foot controller. Unlike the floor version of the Helix, the separate floor controller does not have an expression pedal.
While many other pedals work with the Helix, the Mission L6H allows both treadle and button control. It connects to the Helix floor controller or to the main rack with 2 standard mono TS cables. 1 jack deals with the treadle and the other deals with the toe switch.
The amount of control it gives to the Helix is staggering. It can be just a volume control. Or pressing the toe down can activate a wah, turn on a drive pedal and change the amp model in use. It can be mapped to drive levels within a pedal too, or change reverb mix, or the mid control on an amp.
The build quality is excellent. The treadle is nicely weighted and does not squeak!
To get even more out of the Helix needs a full midi controller. I don't need that and the Mission L6H gives me all the control I need.
Excellent well built product!