plastic keeps foreign pets outside with collar magnet, to be attached to the collar transparent flap, silent action with 360   circumferential seal (TPR) and magnetic clasp with convenient screw top 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