These one-sided decals are perfect for car windows. 3 designs available!
 
Stop/Caution - a bold design with a call to "STOP" and ask "have you checked the back seat?"
Seatbelt/Check - a reminder for parents and caregivers to check the back seat EVERY time.
Thermometer - an example of how long (or not-long) it takes for a child to be in danger if it's just 80 degrees outside.