I use them for my boxer pup and they work great. She's about 45 pounds and the bags are plenty big enough. We have the lavender scented and once you tie them up you can't even smell the poo - which is kind of impressive, my girl is a stinky one ;)
We have two dogs, one large breed and one medium breed. These bags work perfectly for cleaning up after both of them. The bag is pretty durable. We use the lavender scent and after you tie off the bag, you can't smell the poo.