Not sure about that, but let me tell you this...I would not suggest trying to get past the bottom or back tensioner with the heating element.
We did the drivers seat first and had to undo almost all the cover clips and still it was very (very)
difficult to get the pad past the tensioner on the bottom seat.
For the drivers back and passenger bottom and back I just trimmed the heater element to fit the area up to the tensioner.
The results...nice warm seats for these frigid Colorado mornings.
Michael