ADA-compliant shower units are designed for people with limited physical abilities. Showers that comply with the Americans with Disabilities Act (ADA) are designed with a low threshold so that you can enter them unobstructed or so that a wheelchair can be rolled into them.
ADA-compliant showers are one-piece units that have grab bars and a built-in or fold-up seat. A person in a wheelchair should be able to roll up next to the shower, adjust the single-lever handle controls from the outside, and then use the grab bars to move to the seat inside the shower unit. The unit should include a hand shower that can be operated by someone who is seated or standing.
You're not going to find too many examples of ADA-compliant shower units at retailers, but you can find them featured on manufacturers’ Web sites, such as Kohler. Use the manufacturer's search boxes to refine the search by specifying ADA compliant, and you'll narrow the selection. These sites list the cost of the units, installation requirements, specifications, rough-in dimensions, and the actual installation manuals — all valuable planning material.