YBM HOME Square Plastic Wash Cup. Large, Kosher, long lasting, for ritual hand washing. This YBM HOME Hand Washing Cup is used for Ritual Hand Washing. Traditional Judaism requires ritual washing of the hands for a number of reasons including after a full night's sleep, before eating bread with a meal, after having going to the bathroom, during the Passover Seder, or at other times to remove impurity. Approximate Measurements is 5 '' x 5" x 5".