A device is provided for measuring metal inclusions comprising a receptacle for holding a sample of molten metal, with this receptacle having insulated side walls and a bottom wall provided with an exit opening. A ceramic filter element for collecting inclusions from the molten metal is positioned within the exit opening and is bonded to the top face of a solid refractory or metal annular support ring with a portion of the support ring top face extending laterally beyond the filter element and engaging the bottom face of the bottom wall of the receptacle around the opening. The filter element and support ring assembly is held in place by a detachable retaining means which is adapted to securely hold the support ring in leak-tight engagement against the receptacle bottom wall with the filter element positioned in the exit opening.