The second phase of UN r 129 contains different categories: the ‘i-Size booster seat’ category and the ‘specific vehicle booster seat’ category.
The ‘specific vehicle booster seat’ category allows for widths above 44 cm, so that the fit in terms of height and width depends on the vehicle and should therefore always be tried out before purchase.
Specifically for stature heights above 135 cm, the headrest of the booster seat can in some cases touch the vehicle body. This is sometimes the case with sports car models but rarely with family cars. BeSafe recommends to test-install the seat in all positions in the vehicle you intend using it in and check the installation, available space in the vehicle and position of the child to see if it is acceptable for your situation.