What is a top tether?
According to carsafety.org: a top-tether is simply a strap that connects the top of the car seat to an anchor mounted in the vehicle at a location behind the car seat, usually the parcel shelf or a point on the floor of the cargo area. It is designed to prevent the forward movement of the top of a forward-facing car seat in a frontal crash. This reduces the head excursion of the child, and can reduce the chances of injury. Vehicle owner’s manuals often detail the locations of these anchors. They can be on the bottom of a seat, in the floor, on the rear deck of a sedan/coupe, in the cargo area roof of a wagon or SUV, and may even route through a fabric loop in some pickup trucks. Top-tethers MUST NOT be used with rear-facing infant or convertible seats, unless it is SPECIFICALLY mentioned in the owner’s manual.