My 9 lb Chiweenie fits great in the Small size fundle. I've taken this into crowded markets, on public transportation, and the vet hospital. In particular, the fundle was very handy when my dog had to go to the vet for a minor procedure and we were advised to let her rest and avoid walking for the evening. I carried her in the fundle from the hospital back home. Other bags are heavier/bulkier, so I don't think I could've lasted 30 minutes in those. I can easily sling the fundle on one side and my purse on the other side of me.
A friend of mine suggested the fundle, as her extra small size Yorkie loves her little bag, going on 3 years. So while the price tag is high for a dog product, knowing that these bags last years without much damage made me more confident in my purchase.
-Review on Amazon