"Ounce size" refers to the amount or volume of something, specifically measured in ounces. It is a way to describe how much of a particular item or substance you are referring to. Full definition
Our unique feeding bottle is available in 5 ounce and 9 ounce sizes in a variety of colors and decorative options to brighten baby's world! (tommeetippee.ca)
Easily store up to seven individual meals for your baby in the 2 - ounce or 3 - ounce size options. (thetoddle.com)
One 40 - ounce size lets you do 106 average size loads of laundry. (thetoddle.com)