Suction cup feet need a flat, smooth surface to hold. Plenty of showers do not offer one: textured safety tiles, small mosaic tiles and grout lines all give the cups something to leak around, and the base unit can creep during a transfer.
The shower disks fix that. Four round plastic disks are glued down where the suction feet land, giving each cup a clean, flat patch to grip. Once they are in place the base sits where you put it, every time.
They are bonded with an STP polymer based adhesive sealant, which sticks to acrylic, fibreglass, ceramic, marble, granite, hard plastics and metal, and works in a wet room. It is a small job for an installer or a handy family member, and it is permanent, so mark out the positions with the chair in place before anything is glued.
