Sport buggy max user weight 15 kg recommended minimum age new born pushchair weight 8 kg backrest multiple harness system 5 point safety harness slider not adjustable series britax b agile wheel settings swivelling lockable number of wheels 4 safety bar with bumper bar footrest adjustable dimensions 100 x 90 x 58 cm dimensions folded 30 x 71 x 58 cm included in delivery canopy shopping bag bumper bar application city