Types of pet barriers:
Mesh: These barriers in general are made pretty poorly and I don't recommend them AT ALL. Stay away from these unless you have a small dog or drive a very small car! They are extremely flimsy and can actually be dangerous for your dog, should they get their nails/paws stuck in it.
FROM MY EXPERIENCE, THE BEST MESH BARRIER IS THIS ONE:
The Pet Net Brand Safety Barrier - NEW vehicle barrier for dogs, Adjustable & Affordable! 47" W x 24" TFROM MY EXPERIENCE, THE BEST NYLON BARRIER IS THIS ONE:
Bergan Pet Travel Back Seat Barrier
Metal: These barriers are meant for large SUVs (Honda Pilot, Toyota Sequoia, etc.) or covered trucks. They are very powerful and are meant for supporting several dogs, but are unfortunately the most expensive barriers. I really recommend them if you drive a large SUV or have very large dogs (Newfoundlands, Mastiff, etc.).
FROM MY EXPERIENCE, THE BEST METAL BARRIER IS THIS ONE: Petego Walky Guard Car Barrier for Pet Automotive Safety
Best of luck with your pet barrier shopping and remember to keep you and your pets safe out there on the road!