Milk level indicator

I'm a little late for the icebox challenge, but thought I'd do a really simple little indicator for milk and juice.

If you check the level when the carton comes out, move the indicator and pop it back in the fridge. Helps you see how much is left at a glance. Add two rubber bands. :)

Also works with bottles and pesky pringles cans. Anything you can get rubber bands around really.