I have the Shutt Kool vest. And I like it!! I eat under armour under it, and it has the "same type" of material on the back (I know it's not identical patents and all
) but it wicks mositure and really doesn't feel as hot as my UMP protector used to. I also have not used the ice packs, but have talked to someone that had and they had a fellow blue that brought fresh ones about the 4th inning and it seemed to help in the OKC heat. I have not worn the K2 but have seen people take hard shots just under it and don't think I would risk the injury for the heat difference, but JMO