These pet carriers are i a t a approved and have been approved by bidair pet lounge ensuring no hassles when pets need to fly available from large to extra large (for bigger dogs like labrador retrievers) metal front gates that clip in securely with screws on the sides, air vents on the sides ensure sufficient ventillation 4 additional clips for added safety they come with wheels to make moving larger breeds hassle free medium r2500 large r2900 x large r3500 x x l r3850