Proposal to amend UN R129 concerning Enhanced Child Restraint Systems. Modifications include: adjusting shoulder height dimensions in Annex 18 table 1 to align with anthropometric data for children from 40-70 cm; permitting one additional insert layer for infants below 50 cm; establishing minimum stature of 35 cm; and adding transitional provisions regarding type-approval acceptance timelines from September 2028-2029. Changes address fit concerns for premature newborns and small children.