Inside is absolutely hollow.

The appearance of the drain pipe is the same — a cylindrical product that does not differ in large size. Inside is absolutely hollow. The purpose of such a product is to ensure the directed removal of rainwater and melt water to the sewer system. In most cases, for greater efficiency, a funnel is installed at the top of the drain pipe — it is, in fact, it provides the correct direction of water. It is also a connecting element of the drain pipe and gutter.