These are fairly common panels just not as talked about as often compared to wool and foam.
A Swiss panel is basically a tube of felt that is filled with wool. This tube is the shape of the saddle’s panel. It can have gussets (a wedge-shaped piece of leather inserted into a panel to create depth), or be upswept (curve upward with the back of the saddle). The felt walls are about 1/4” thick and create a very smooth panel bottom for the horse. Felt is a natural pressure point-alleviating material; it is also shock absorbing. Wool is inserted into the panel to create depth, shape and firmness.
These saddle panels require less maintenance than regular wool-flocked panels. This is a very common set up for Italian saddles. The most common saddles with these panels are: Amerigo, Erreplus, Prestige, Harry Dabbs, Jaguar, and Verhan.
A hybrid panel is a layered panel of different materials. They can be made with a mix of felt with foam, felt with wool, foam with wool, and other materials like air cells/fibre material with wool. The bottom layer (the one closest to the horse) is usually the felt or foam and then wool on top.
So the bottom of the panel is very smooth and flat but can be flocked for shape, balance, and depth. The benefit of these panels is they require less maintenance because the bottom layer will always provide cushioning for the horse’s back. There are no lumps or bumps to the panel.
The panel is less likely to get warped, lose shape, collapse, or stretch out of shape. They provide a bit more shock absorption then just a wool panel. They are not as easy to do minor adjustments to match a horse’s back.
Many saddle companies have done versions of these over the years. Thinline even did panels lined in their trademark material. I have done some with my “air ride” material with good success.