How tight does the harness system need to be on my child?

The harness system fit is vital to ensure that your child will remain in the car seat.  The proper setting for this system is snug to one adult finger placed at the collar bone of the child coupled with the harness clip being placed at arm pit level (top of the plastic clip is just above the nipples).  It is important to know that there needs to be a minimum of clothing or material between the harness strap and the child’s shoulders.  An improperly fitted or impaired harness strap will not hold the child.