Narwhal USB Heated Slippers | $34.99 | These Narwhal slippers are made of cozy cotton and polyester, they will keep your feet warm when you use the detachable USB cable to plug them into your Mac, PC, or other USB port. USB cable is 57" long so you can stretch out and still keep warm. One Size fits most, up to Men's size 12. Each slipper measures 12" x 5". Go wireless for $49.99.