摘要 |
<p>The device i.e. hollow block or brick (2), has a male part (4) and a female part (5) forming a trapezoidal under cut, where the parts are extruded on faces of the hollow block or brick and positioned above or against each other. Width (L2) of the male part is less than width (L1) of the female part in order to facilitate the passage of the male part into the female part to allow creation of interstices during fitting the male part and the female parts at certain angle.</p> |