Kawashima-ya This is a koji lid made from 100% domestic natural Japanese cedar. It can be used to make 1kg of koji. The size is as shown in the photos. Please refer to the Kawashima-ya website for detailed instructions on how to use it. I am selling this because I bought a larger size. I only used it for making koji, so it has a koji smell, but I have not used any detergents. I would appreciate it if someone who understands this would like to purchase it.