Your Plum lets you choose from two different pour sizes for each wine: TASTE and GLASS. By default, taste is 1.5 ounces, and glass is 5 ounces.
To change the pour size, touch the SETTINGS button, and then click POUR SIZE. Use the + and - buttons to change the taste size on the left, or the glass size on the right.
You can change from oz to ml, by selecting ml at the top of the POUR SIZE screen.