A friend that knows we ferment foods gave us this crock. It was made by her co-worker. It is a great design, you add your veggies to be fermented in the center of the big pot, then use the 2 half moon pieces to weigh them down under the liquid. Next you add water to the trough around the top of the crock and put on the lid. The lid is designed to let the gases out, but not let oxygen in. Great work, I will be putting it to work soon.