Review on Convenient Refillable Containers: Your Must-Have Essential Cleaning Aromatherapy Travel Accessories by Ryan Frazier

4 oz bottles DO NOT hold 4 oz. I filled one almost to the neck, and I had 1 tablespoon of liquid left to go in the bottle. I would call this a 3 ounce bottle because the liquid needs to stay under the neck to make room for the atomizer mechanism. Very disappointed. 8 ounce bottles hold 8 ounces. The liquid didn't quite reach the top of the bottle, which is good because it leaves room for the atomizer mechanism without overfilling the bottle.