A reader of "Tigerfeeling – The perfect pelvic floor training for men and women" (E-Book, Südwest/Randomhouse) sent me this link with the comment: "Another stupidity from the pelvic floor press." The Vagina is not a muscle that can be trained with such gizmos.
The vagina is embedded in much greater musculature: the levator ani, the one and only pelvic FLOOR. FLOOR. FLOOR. A FLOOR can raise and hold organs, a pipe cannot. – And the Levator Ani makes for the sexiest butt and the best orgasms. I have tested it all. There is nothing like one's own core musculature. So: go for the real thing. TIGERFEELING.