Read Leviticus 15:20 Using Other Translations
And every thing that she lieth upon in her separation shall be unclean: every thing also that she sitteth upon shall be unclean.
And everything on which she lies during her menstrual impurity shall be unclean. Everything also on which she sits shall be unclean.
Anything on which the woman lies or sits during the time of her period will be unclean.