Fill the gaps with who, whose, which or that.

The Californians have come up with a device for people JXUwMDJmJXUwMDFmJXUwMDA3 have their own small swimming pool JXUwMDJjJXUwMDFjJXUwMDA5JXUwMDE1 should transform their lives as much as those indoor exercise bikes JXUwMDJmJXUwMDFmJXUwMDAxJXUwMDBhJXUwMDBi were so popular in the 1970s did. Swimming which is recognised to be one of the best ways of keeping fit is impractical in pools that are too small for serious swimming. But the Hydroflex is a new device JXUwMDJmJXUwMDFmJXUwMDAxJXUwMDBhJXUwMDBi can keep swimmers in the same spot and still allow them to do all the strokes. It consists of a plastic bar JXUwMDJjJXUwMDFjJXUwMDA5JXUwMDE1 is attached to the side of the pool by two lines and to the swimmer by a waist belt. The swimmer JXUwMDJmJXUwMDFmJXUwMDA3JXUwMDFjJXUwMDE2 legs are protected from the lines by the bar remains stationary while swimming. It sounds like an activity which is only suitable for people JXUwMDJmJXUwMDFmJXUwMDA3JXUwMDFjJXUwMDE2 desire to keep in shape helps them to ignore the taunts of neighbours JXUwMDJmJXUwMDFmJXUwMDA3 happen to spot them in the pool.