The core activity of FMB Group GmbH consists of two main areas: 1. Cleaning services: The company offers professional cleaning services, as indicated by the mention of 'FMB Reinigung' and the website 'www.fmb-reinigung.ch'. 2. Natural stone processing and distribution: The company is also active in the processing and distribution of natural stones, as indicated by the mention of 'FMB Boden' and the website 'www.fmb-boden.ch' as well as the designation 'Natursteinspezialist'.