Ki Mobility Axiom SP visco cushion is designed to provide increased immersion, using a Viscoelastic foam instead of the Hydrolite fluid bladder. Axiom has anthropometric design and also has two small areas where foam is removed under the Ischial Tuberosities to facilitate immersion. Axiom comes with a pleated 4-way stretch inner cover with self-sealing zipper which is water resistant and is easy to clean.