Patented in Malaysia for Engineering Load Bearing Wall. Special tongue and groove features for easy installation and self-alignment. Air gap feature for good heat and sound insulation. Specified manufacturing sizes of blocks allow for 10mm (3/8 in) mortar joints and satisfy the concept of basic size, i.e. the basic scape to be occupied by the block and its share of the joints, in accordance with BS 3626, “Recommendations for System of Tolerances and Fits for Building”.