Wonderful for my Rat Terrier and easy to assemble. Tires are rubber that can be pumped up to the correct PSI for a smooth ride. Tires come off and carrier collapses for easy transport and storage. Zippers and velcro are strong and durable. Canvas is heavy. Screens are great to let the fresh air in. Options of plastic over the screens is nice to protect from road debris and dirt/mud that my rear tire kicks up. The inside has a lead to attach to my dog's harness. I add a little extra cushioning for her to lay on as well as she is 18 years old and deserves only the best. She is 16 pounds with long legs. She fits in the trailer very well but I wouldn't use it for anything larger. This carrier isn't too big or too small for her and was what I was personally looking for. I did have to purchase and have my bike shop install a special axle for under $12 so it would work on my road bike but it was so worth it. After a few short test runs, my dog acclimated to it well. Now every time she walks by it in the garage she wants to go on a ride. One of the best purchases I have made. More time and adventures with my best friend! I did attach flashing lights by the reflectors as lights save lives. I also make sure the carrier is bright color wise so she is easily seen.