This is the best pet carrier I have ever purchased! It is VERY sturdy! My last one broke while I had my cat inside and was traveling! This one has been strong enough to carry my cat and dog, alternatively. The wheels are great! They have never come off! The backpack option works great. The straps are padded and are strong enough to hold either my cat or dog. The handle is great and has two settings. I am buying an extra one soon! My cat is a tabby cat and my dog is a maltipoo and this works well for either one. The dog is about 5 lbs and the cat about 8lbs.