Dogs
3-Flap Steel Large Dog Door for Exterior Doors with Sliding Lock Panel, Energy-Efficient Insulated Pet Door, Extreme Weather Doggy Door with Telescoping Tunnel, Never Rust（Pets Up to 100 Lb）
A heavy-duty, 3-flap aluminum pet door built for exterior doors and claimed to fit pets up to 100 lb. Good insulation and a sliding lock—just be ready for a careful install.