We pack our cups in temperature-controlled boxes with proper insulation and dry ice to keep them frozen for more than 50 hours. This means they will keep frozen during transit and even for few more hours on your doorstep before you get home. Make sure you put the cups in your freezer as soon as you get home. Do not touch the dry ice when you take your cups out of the box. Simply leave it in an open space for dry ice to disappear.