Can insulator made of foam with polyester surface.
The reason your drinks stay cool is not because of an insulating effect, but rather the water vapour condenses on to it when moist.
The magic behind how cold cans keep everything else at bay has nothing do with insulation - instead we owe our cooling powers entirely due solely down...to humidity! When warm air touches any object made primarily out metal (including aluminum), moisture gets forced into their crevices where tiny pores exist between cells which can then escape easily through narrow openings.
So OK, the Can Cooler does insulate your can, but more importantly it protects your can from condensation, which will warm up the drink in your can much faster than just being in a warm environment.
SAY NO TO WARM DRINKS THIS SUMMER.