Asymmetrical sitting postures are hard to cushion, and the STX exists for the clients who have one. It is a modular cushion: a positioning base carrying foam packs, with a comfort wrap over the top whose ribs flex around uneven contours so the surface follows the client.
The foam ischial well keeps the cushion light while giving the sitting bones a defined place to sit. Femurs can be dropped individually where a hamstring is tight and pulling the pelvis out of position, and the pre-ischial shelf adjusts to hold the pelvis forward. Thigh supports can be offset for a windswept posture, and build-up pads correct an obliquity.
All of that happens at the fitting, with the client in the chair, and the components can be revisited later as things change. It is a cushion for a therapist who needs to work in detail.
