Invacare Matrx PS Superior Positioning. The Invacare® Matrx® PS cushion is designed to provide superior positioning, stability and comfort. The design features an anatomically contoured shape with a unique waffled ischial relief recess and an innovative reversible outer cover. Show more Contact UsFind a Store Technical specification Downloads Website Script - Matrx PS Cushion.pdf (99.93 KB) Matrx Seating Catalogue (11.08 MB)