While grooming their coats cats swallow hair that their stomach cannot digest in order to get rid of this hair cats like to eat grasses that help them to create hairballs from the tufts of hair normal grasses tend to be too hard however which can cause pain the specially developed gimcat cat grass avoids this problem the gimcat hydro grass in the practical growing tray is especially simple to use due to the water holding hydro granules it is enough to water it once and within a few day