The seat edges specially designed for the Tasso water mattress in widths of 160 and 200 cm are made from stronger special foam. They allow they therapist and the user to sit on the long side of the water mattress without sinking in. Please note that the width of the water mattress will be reduced depending on the width of the seat edges. Due to the technology used in manufacturing, the 160-cm-wide water mattresses have a seat edge of 30 cm per side; the 200-cm-wide water mattress has a seat edge of 20 cm per side.