Mountain Buggy Helmet The Mountain Buggy helmet is the perfect accessory to keep your child protected while riding the Unirider or Freerider stroller board.  Key Features -Matte black finish -Longevity - recommended age range of 2-7 years (age as a reference only) -Two sets of protective safety foam -Thick foam padding - 10mm (0.4\") for a head circumference of 48 - 51cm (18.8 - 20\") -Thin foam padding - 7mm (0.28\') for a head circumference of 52 - 55cm (20.1 - 21.6\")