To start off, what is a Child Passenger Safety Technician? A CPST has been trained specifically on the topic of child restraints and safety within a vehicle. They can spot problems and know the specifics about seats and cars on the market. They make sure that a child is in the correct seat for their age, height, and weight. With upwards of 80% of child restraints being used incorrectly, a CPST educates parents on the correct use of seats and shows them how to properly install them.