We have a Cavalier King Charles and found the small backpack was a little too large. We purchased a cushion and now he fits perfectly in the Backpack.

My sport sack is a size large, my dog fits perfectly in it when we ride bike. However, if we go for a walk she would sit a little too low. The booster block fixes that problem. If your dog, like mine, is in between sizes or just doesn’t sit quite right in the sack I would look into the booster. It’s definitely worth it.

Great product, very convenient thing!

I got the small size of the air2 pack but it is a little big for my toy poodle. put this booster in and works great. so now I can use the pack for either dog, my toy poodle or my 17lbs schnoodle.

My toy poodle has congestive heart failure. He cannot enjoy exercise and cannot go up the stairs. I bought the K-9 sport specially for the stairs. It has worked out really well and we don’t just use it for the stairs. I’ll give it seven stars.