Ideal for adding concrete within for strength.
Tradies often refer to these blocks as being 400 x 200 x 200mm in size because the mortar width is also included in that measurement, and it is easier to work out bulk quantities required. The actual size is 390 long x 190 wide x 190mm high.
The “full” refers to the size of the block which has two large cavities within the block. These blocks are not ‘solid’