two is just a starting point [SEP] they are ok the main thing is that you really cannot do much with just two at a time if you use one on each side you end up with more of one little hill on each side with two on one side you can get a bit more of a cascade volume fall but then you have to stop and do them on the other side at a minimum two sets will get you some decent volume up front or whatever section you choose to use them i think though i would probably prefer to create a total up top volume look more sets of these the next kind of issue is remembering to use them i am straightening my hair if i am drying it and you really have these in during that process because of the smoothing brush process that is part of that so then i have to remember once i am done drying to go back and use these before i do any flat iron or curling thingsto get some up top volume they do kind of work i would just suggest determining how much volume you prefer in terms of where all on the crown and order based on that for me it is on each side up front then more rows of one behind it