The company Beltrami Natuursteen (formerly known as "SDS kasseien" or "Kasseien De Smet") has been part of the Beltrami group since 2008. Their current stock is mostly composed of new materials, but they remain very active in the recovery of pavers. To limit the need for cleaning and sorting, they mainly acquire homogeneous batches.

Their flagship product is the “classic” Belgian paver, the square or rectangular porphyry paver. But they also have other varieties and formats, in smaller batches. The manager Thimothy Beuselinck explains that a customer who is open to less popular or less known types of paver can do excellent business. SDS kasseien also regularly supplies public contracts.