Whyhoose Dets Large Cve the freedm the cat door prl be more free at hme! Fi Door Thicess and Cat Sizes: > Suible for cat lightr tan 17.4 lb and waist cirmfe is up to 50mm thick; 4 Way Locking: no in&no out( fully locked) free in&out( fully ope/br> in only out only Function Inruction of the Switches: 1. Turn Red andeen swites tbo sides, pet is prvted from eering or exing house. 2. Trn Red and Gren swies to right side, pet is alwed to nter ouse, butprens allwed to exit house but prent from enering uxit a time. Depet Car Door Specificons: Material: ABS plastic Color: Wite Style: Flap Outer Size 9.25" x 9.92" x 2.16"(W x H X D); Inner size: 7.08" x 7.48"(W x H); Weight: 0.52 kg Fit Cats up to 20 lbs （The waistne less than 6cm)