electromagnetic identificationkeeps other pets outside with collar magnet for access permission transparent flap, silent action with special sealing and magnetic lock with turn-lock fastener incl. tunnel element depth 10–35 mm can be extended with more tunnel elements total measurements 21.1 × 24.4 cm cut out size 16.5 × 21.6 cm flap size 14.7 × 15.8 cm battery-operated (9 V battery not included) 3 years guarantee plastic