Both of my dogs loved riding in the trainer! At this point they are pros because this is our 4th K9 sports sack! As the person carrying them, I love this product because it has all of the same great features as a normal K9 sports sack, but just the necessities and no extras or frills which is perfect because it makes it light weight and easy to bring with me everywhere! My trainer bag is size large and both my corgis fit into it! One is 30 lbs and the other is 20lbs, but since corgis are long they both fit in the large!