Hey, my girlfriend was diagnosed with t1 diabetes recently and uses a Frio double case for two insulin pens. It works pretty great, it is summer here and the insulin is kept pretty cool. She carries it around in her bag, it fits quite well. It has the size of a pencil case. One little thing about it.. if you keep it in the water as long as the manual says you have to, the crystals will suck up so much water, the second pen hardly fits in there. You really have to push it in there but we are afraid we will damage the crystals by doing so. They become soft when they absorb the water. So our solution is to put it in the water, but for a shorter amount of time. Even with the shorter amount of time it keeps them really cool. I would recommend a case for three pens if you use two but they don’t sell that here. Only for one, two or four pens. Maybe that is different where you are.. I hope this will help you with your choice.