H-Section replacement knurled knob for both Round and Rectangular Aluminum Pet Patio Doors and Aluminum Sash Window Pet Doors. Sold individually.
How to Measure Your Ideal Pet
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.