Seat belts

About 2 weeks ago we swapped the boys from a 5point harness to an adult lap-sash seat belt and in doing so, converted their seats to booster seats.
They weight guidelines for the conversation is 18kg.
Depending on the time of day they are weighed....
Ethan is 17.9-18.4kg
Ben is 16.9- 17.5kg

We figure that's about right....

They are happy with the move :)