MK KOLEKT VENT ventilation blocks - natural ventilation system. Ventilation blocks are made of expanded clay, it gives good sound isolation to ventilation system compared to metal systems, also high fire resistance. Blocks are lightweight, it makes installation of natural ventilation system fast and easy. Same as MK KOLEKT chimney blocks, MK KOLEKT VENT ventilation blocks are 24 cm height. Quality of MK KOLEKT VENT ventilation blocks are approved by issued CE certificate of conformity.