They Are Portable, Lightweight, Safe, Environmentally Friendly And Durable, Protecting Your Pet From Harm. Windows Have Multi-Ventilation Design, Comfortable And Breathable, Pets Will Not Feel Stuffy. And There Are Mute Wheel, 4 Universal Wheels, Smooth Running, Flexible And Silent, 360 Degree Rotation, Can Enter And Retreat. Aluminum Alloy Rod, Sturdy, Durable, Multi-Stage Adjustable Design. And Textured Alloy Two Zipper Headfine Workmanship, Smooth And Wear-Resistant, Long Service Life, Pet Easy Entry. The Double Straps Are Designed With Plastic Buckles To Keep You From Being Heavy When You Are In The Backpack And To Fix The Position Of The Backpack. Package Includes:1 Piece Pet Trolley Case