For Vinyl Insulated Pet Patio Doors/Vinyl Top H-Section
Medium H-Section length is 10 ¾”
Extra Large H-Section length is 14 ¼”
To determine the correct size door simply measure the width (A) and height (B) of your pet.
(A) Measure the widest point of your pets shoulder
(B) Measure from the top of your pets back (just behind his head) to the bottom of chest.
FLAP SIZE DETERMINES ALL REPLACEMENT PART AND PET DOOR SIZES: 5"x 9-1/4"(S), 7-1/4"x13"(M), 9-3/4"x17"(L/XL), 15"x23-1/2"(XLG/SL)