We use hard composite gypsum. After detailed testing, the hardness of our gypsum is 45~50D, while the hardness of other brand gypsum is 20~30D. The most obvious difference between our gypsum and other brand gypsum is that our nests will not be chewed by the ants after a long period of time, while other brand gypsum nests will be chewed by the ants and become pitted.