A hollow concrete block is a block that usually has two or three hollow spaces between its walls, that is why it is called a hollow block. The number of hollow spaces depends on the width and length of the blocks and the bigger the size of the block is, the more it has hollow spaces in it.
Hollow blocks have different shapes and sizes according to your use. These concrete blocks are mostly used to build walls in the construction industry. If you only need information about the concrete blocks you can read the article