"It's Mom Time" Interchangeable Door Sign
The perfect sign for when you're in your room! This interchangeable sign includes three discs for Come on In, Please Knock and Do Not Disturb, and they're also painted to match traditional stoplight colors, making it useful for non-readers as well.
Disc is held in place with a dot of hook and loop, and two more spots on the back easily hold the two unused discs, so it's all together for you right there.
Overall size is approximately 2.75"x6"