The key to making great compost fast is to have your organic materials contained so that a heat core can be built quickly. The dimensions of the ComposTumbler, in all sizes, have been calculated for maximum efficiency in building a heat core. As the drum of the ComposTumbler is turned, the materials inside mix and the core is stable. Air and moisture are the other two essential ingredients. The ComposTumbler is designed with air vents on the sides of the drum and on the door so air flow is unimpeded during composting. Drainage units on the door allow for any excess moisture to escape so materials won’t get soggy. This company manufactures four different models.