Host FREEZE Beer Glasses, Frozen Beer Mugs, Freezable Pint Glass Set, Insulated Beer Glass to Keep Your Drinks Cold, Double Walled Insulated Glasses, Tumbler for Iced Coffee, 16oz, Grey

It took a year of trial and error to perfect the exact "ultrasonic welding" geometry that joins the clear plastic parts together and allows this cup to mimic the elegant shape of a pint glass. The plastic had to be engineered to handle expansion and contraction from the gel freezing as well as extreme cold and warm conditions.