Stirrup straps

Can affect the rider's pelvis tilt, refines the twist, and slightly deepens the seat. It goes under the front of the seat, with the wide side toward the pommel and the pointy side toward the rider. It can be moved forward/back for a greater effect.
Riders who have a low pelvic floor may not like the bolster. For those who are looking at the product to tilt the pelvis, one of the other rider balancing aids will have a great effect without discomfort.
To install, release the velcro under the front center of the seat, then tug the seat back over the front dees. Place the bolster and press the seat back into position, making sure all is still symmetrical. Replace the front velcro tab and push the seat back over the front dees. This last part can be difficult, especially when the saddle is new - to make it easier, pull some twine or a shoelace through the dee to give you more leverage.

Velcro wedge to reduce seat size about 2cm (1/2-3/4"). It has a bit of cushion as well. To install, carefully pull the seat forward over the cantle. Don't go too far because there are velcro tabs at the bottom of the seat. Position the seat reducer as desired and press the seat back into place. You may need to lean across the back of the seat to push it down far enough for the velcro logo on the cantle to grab.

These slip on over girth straps if there is a bigger gap between the bottom of your pad and the girth (short flap saddles or larger horses). They can also be ordered with the top layer to match your saddle color. Backing options are neoprene, black, brown, or white wool blend (or exclusive sheepskin, but that's really more for show than practical use and typically order along with either a zalea or Cagliari/Maremma saddle.)
Sold as a pair.

Wedged shim inserted between base and closed panels. Perfect for those who want the classy look of the closed panels (especially with a matching color/material) but need a little lift in front to balance the rider for horses who might be downhill where the saddle wants to side or who have less curvature than the Ghost base. These work great with velcro opening panels too, and sometimes are a bigger solution than the felt shims that can go inside the panel. Sold in pairs.