This set of two planters is made from EPP (Expanding Polypopylene) which is highly insulating and protects roots against frost and heat. Your plants won't suffocate in the planters due to the "breathable material". EPP is strong, light and extremely durable. Their unique composition prevents corrosion and increases resistance to harsh and extreme conditions such as freeze – thaw. Coming with one large planter and one medium planter, this set can make a beautiful focal point in your garden.