Black Cap Liners cannot only be used to replace your worn out gourd cap liners but they make your gourds interior darker, like a natural cavity. Made from the insulation material Depron (a recycled material), they snap in place and create a tight seal. They let in practically no light (unlike the manufacturers lid liners) and should last many seasons. They are laser cut, 100 percent water repellent and do not conduct heat. They fit perfectly in Excluder, Super and Troyer gourds.