What Do The Container Sizes Mean?

The numbered containers are equivalent to the number of nursery gallons per container. 

Container sizes referred to in gallons are shipped in equivalent nursery trade sizes, which may vary in actual volume. This is standard nursery practice. Even still, we understand this may be confusing to understand at first. Below we've made sure to include a link to a chart that helps to explain: https://www.octoraro.com/faqs/container-sizes/

Keeping in mind that volume may vary, we have also included a chart that cites the ranges by both cubic inches and cubic centimeters.