These incredible mugs keep your hot liquid beverages hot and you Icy or cold beverages cold. Pretty much they hold your drink at a temperature for a time then nothing lasts forever but if you leave the lid off it will expedite the cooling or warming process. These mugs are also pretty nice and with the port and starboard colors leading you to the path of knowing your rules of the road. You can use a green one when going to work and a red one when coming home or who cares whatever you want. Its your life. Cheers!