Fireproof filters for foundry engineering (parts for engines); fireproof filters for foundry machines or casting equipment (machines), in particular to prevent the penetration of contaminants when casting; fireproof filters being parts of machines, included in this class, in particular for grey cast iron, nodular graphite iron, cast steel and aluminium; feeder sleeves for use in foundries (parts of machines); feeders (parts of machines) being parts of casting equipment, in particular exothermic and insulating push-in feeders and insulating feeder sleeves