Good but expensive
I do not know if these biscuits really help with calming a dog but my dog certainly enjoys them. However they are expensive so I alternate them with the Barking Heads Nitienites from Zooplus.
They are a good way of getting her back in after letting her out last thing at night. I am unsure how many one should give a dog in order to have the calming effect - perhaps more than one would be better.