Cat Window Screen Spacer

Spacer to fill the space in the window frame around the cat window screen. The spacing in my window was 18.3mm, the cat window screen was 10.1mm.The cat screen window this is "Ventilated Pet Door for Window, Fits 32"-38" Width Window, 2-Min Install | Aluminum Frame + Stainless Steel Mesh | Breathable Bug-Proof | Magnetic Closure Window Cat Door, Cat Door for Window Insert" by YOCHEE