They're 20 ounces so nearly twice the size of an average drink. Even energy drinks which are typically bigger are usually 16 ounces (though sometimes 20). Looking at the website the highest-caffeine version has just under 160mg in 20oz.

Regardless, not sure what this has to do with the overall point, which is that you could consume multiple "high-caffeine" drinks and still be well under the amounts discussed in this study.