This thing is freaking awesome!! I have only used it a few times but so far I am over the moon happy with it. Where I work I am unable to store my milk in a fridge so I have to bring a cooler bag with ice packs and just A LOT of extra gear to keep the milk cold. But with this I just have been filling the inner part with ice and then pumping and keeping it in the bigger chamber and it works wonderfully! By the time I pump the first time to the time that I get home and am able to get it in the fridge is normally 10-12 hours and the inner chamber still has some ice left in it. I have not tried pumping using the lid and inner chamber but that is next on my list to try. Just really happy with this thing so far. It will be my baby shower gift for any new moms from now on!