This extension strap is suitable for child restraints manufactured from march 1993 onwards (if they are manufactured prior to 2010 you shouldn't be using them now anyway). Some vehicles require an extension strap to allow a tether Strap or upper anchorage strap on a child restraint to be connected to the child restraint anchorage in the vehicle; Usually station wagons and sedans. This is most often required for seat in the rearward facing position. This extension strap will work with all Britax seats as well as other brands.