The Mushbox Kit is ideal for beginners wanting to learn the casing method. This proven, famous kit uses straw and soil to create a healthy bed for the mushrooms to grow, creating a large fruiting area that produces beautiful mushrooms for up to 3 flushes. Comes with 1 half gallon jar of sterilized rye grain, straw, casing soil, casing starter, spray bottle, mixing bag and the box and dome lid. A casing is simply a shell that provides moisture for the substrate. There are many types of casing materials