This is the last set I ordered (clear 5 pack), but I've also ordered and used the blue boxes from the first link I included. Most of the ones I have are from Heathrow Scientific as those are the ones I find on Amazon most often. There is a some headspace, but not enough that the vials fall out of their spots if you flip the box over. I want to cut out a little foam to place on top at some point to really stabilize them!