On the package they talk about the super slick outer layer. They also talk about the felt, soft grip, and leather. They say to stack what you want on the tab-base, and insert the screw from the back. To me the back would be the hand side and the front would be the string side. They never say to put the light color layer on the string side so I am not sure if the light brown layer is the super slick outer layer or if the tab base is the super slick outer layer. The both feel slick, but the dark base layer is thicker.
So I got on the net and I found the Saunders web site. Unfortunately for me it adds to the confusion.
Now on the web site they show a dark face in one pic on the string side. Then in another they show the layers with a light color plastic layer included as one of them and located like it would maybe be behind the dark tab base and would have the other layers behind it. They show the screws on the string side. They show as pic of the back of the assembled tab and they have the felt on the hand side. They talk about the felt or leather absorbing sweat. In the description they talk about the preassembled version of the tab having the felt between two layers of plastic. However, in the photo for the preassembled tab they show the felt on the back also. The pic's don't show the light color plastic anywhere I can see on the tab, and only seem to show it as a layer option I guess. The pic of the string side kind of looks like there is a layer over the base frame, but I can't tell for sure.
They also have a single layer tab that looks just like the base of the pack tab with the holes and all. However, it is light brown like the layer included in the pac tab, and not dark brown like the base frame of the pac tab. That makes me wonder if they just have different colors or is the light brown color the super slick surface that should be contacting the string on the pack tab, and that same light colored plastic is what they use on the single layer tab.
I can play with the layers for what I like, but it would be good to know what surface goes against the string for starters.