Underpads Pads

What do I need? (Tablets of a chair)?
IDK what to get for my saddle Roper. I think it is quite wide, is everything! And one of the guys who gave it to me said to get a heavy pad. Now, not used for rope, only trace / education. I also ride different horses with him. Some of them are kind of wide horse. IDK how thick saddle pad available. If I put a thick pad, then have the chair form very tight in some hroses. But if it's something too big and I have a slim keyboard, rock and could be uncomfortable. only you have to get two cheaper, or what? Or one that can be thinner, but I could put one of those very fine wool underpads under it? I do not want to use rather than as two pills at a time b / c too make escape. HELP! Uh, polypads are English. Mine is Western.
I would like to obtain a gel of 1 inch thick impact. As it is not too thick and cushion the impacts are very nice and comfortable for the horses.
Underpad Bed Pad Absorption Demonstration