It is made to fit all of the Starbucks sized cups. I use them on Grande and Venti cups all the time. When you first print it it may be a little tight, but as it get used the parts settle and stretch a little, making it go a little farther up the cup. Regarding the 100% infill, you are correct that the grip sections probably do not need that setting, they are very thin. However the connecting structures between the grips are cylindrical in cross section, and making them solid instead of shells gives them a little more strength.