Sentry Calming Cat Collar: https://amzn.to/2KGuTHs
Blackberry's breakaway collar that someone lovingly purchased for her: https://amzn.to/359Cl7z

The Sentry calming collar smells of lavender. When I don't smell the lavender anymore, I assume that it is no longer good. I think we had it on Blackberry for about 2.5 months before it was removed. We noticed that she was considerably calmer about a week after the collar went on.

Blackberry has been more anxious lately for unknown reasons so she has this collar back on her per Louis' request. Louis feels much more safer with her sleeping next to his face when she has the collar on. If you recall, earlier this year, Louis went to grab his bottle of water in the middle of the night. The bottle was right next to the bed. He lowered his arm to grab the bottle and the movement spooked Blackberry who was sleeping near his head. She dug her claws into his face and her claws narrowly missed his eye. If her claws scratched his eye, he would have had to go immediately to the ER.

We have not tried any other calming collars or phermone diffusers on Blackberry besides this. This seems to work for Blackberry so we will continue to purchase it. 4 collars for $18 is a lot easier on the wallet than a single collar for $18.

I do not take any credit for this little collar hack I found it online and thought to share it with you all. Saving money is a good thing :)