 The EU Directive allows "enriched" or "furnished" cages to be used.Under the directive, enriched cages must be at least 45 cm high and must provide each hen with at least 750 cm² of space; 600 cm² of this must be "usable area" – the other 150 cm² is for a nest-box.The cage must also contain litter, perches and "claw-shortening devices".