Typical toilet plungers on the market have a downward-directed “flange”. This design is optimized for pushing on the clog. But it suffers from a tendency to invert and trap nasty water; furthermore, this design and operation mode can easily create splashing.
The improved “Ultimate Plunger”, perhaps counter-intuitively, uses suction instead of pressure. When the plunger is pressed down slowly and then pulled up rapidly about 2″, it does not create splashing. The suction breaks up the clog, usually on the first or second pull. And this design is completely resistant to any “inversions”.