Mifold Hifold: Foldable Highback for Traveling Families

Per 14 CFR 121.311(b)(2)(ii) and FAA Advisory Circular AC 120-87C, booster seats, including the Mifold Hifold , are not approved for use on US commercial aircraft during any phase of flight.

The Mifold Hifold collapses the seat to approximately 9.8 × 13.5 × 13.5 inches — roughly one-quarter of its deployed volume. At 7.5 pounds, the folded seat fits in most airline overhead bins when placed lengthwise, or in a large backpack or suitcase. The optional Hifold carry bag (sold separately) converts the folded seat into a shoulder-slingable package for easier terminal navigation. This folded form factor is significantly smaller than any comparable full-featured highback booster, which typically measures 17–20 inches wide even when not deployed.

The Mifold Hifold is rated for children weighing 40–100 lbs and measuring 43.5–59 inches in height. The minimum weight of 40 lbs aligns with the American Academy of Pediatrics' booster-transition guidance and the NHTSA FMVSS 213 minimum for highback belt-positioning boosters. The 100-lb maximum and 59-inch height ceiling cover most children through approximately age 10–12, depending on build. Hifold recommends that children be at least 4 years old and mature enough to sit properly without slouching for the duration of a trip before transitioning to a booster. Velivolo recommends using a five-point harnessed car seat until the child is older than five, and developmentally mature enough to use a booster seat.

The Mifold Hifold Fit-and-Fold has a useful life of seven years from the date of manufacture. The date of manufacture is printed on a label located on the underside of the seat base and on the product registration card. This seven-year lifespan applies regardless of the purchase date — a seat purchased from a resale marketplace may have significantly less remaining service life than a newly purchased seat. Mifold recommends registering the seat at purchase so the manufacturer can contact owners in the event of a future safety notice. Never use a seat that has exceeded its printed expiration date.

The Mifold Hifold Fit-and-Fold is designed to fit three-across even in compact cars, owing to its minimum body width of 16 inches when adjusted to the narrowest setting. At its narrowest configuration, the Hifold is among the slimmest full-featured highback boosters in the US market. Actual three-across feasibility depends on the specific vehicle's rear bench width, seatbelt buckle placement, and transmission tunnel height. The Toyota Camry, Honda CR-V, and Subaru Outback are cited by CPSTs and families as vehicles where three-across configurations with the Hifold are achievable.

Per Hifold's installation instructions, the Fit-and-Fold requires a vehicle lap-and-shoulder belt and a vehicle headrest at or above the child's ear height. Installation sequence: (1) unfold the seat and adjust all four parameters — seat width, body width, head width, height — for the specific child; (2) place the child in the seat; (3) route the shoulder belt over the armrest through the shoulder-belt guide; (4) route the lap belt through the lap-belt guides on both sides of the seat bottom. The most common error is routing the shoulder belt incorrectly and failing to re-verify all four settings after the seat has been folded and redeployed. Practice the sequence at home before the first trip.

Per WAYB's and Hifold's published documentation, the two seats address different traveler needs. The WAYB Pico is an 8-lb FAA accepted forward-facing harness seat covering children approximately 22–50 lbs; it can be used during flight on US commercial carriers with the aircraft lap belt. The Hifold is a 7.5-lb highback belt-positioning booster covering 40–100 lbs; it cannot be used during flight. Choose the Pico for in-flight restraint with younger children who still need a harness. Choose the Hifold for older, booster-ready children where the travel value is ground transport at the destination — the Hifold covers the 50–100 lb upper range where the Pico ends. The Hifold costs $250 versus the Pico's $349–399.

The Fit-and-Fold is not compatible with vehicle seat positions that lack a headrest at or above the child's ear height. Beyond headrest requirements, the seat underperforms in vehicles with deeply reclined seatbacks, pronounced side bolsters, or very soft cushioning — conditions that prevent the seat base from making full contact with the vehicle seat surface. This category includes some luxury sedans, older minivan captain's chairs, and vehicles with aggressive seat contouring.

The Fit-and-Fold is certified for daily use and meets or exceeds FMVSS 213 for all US vehicle applications. The seat is not restricted to travel use by its certification. However, for families who will use the seat exclusively in one vehicle, the $250 price and the multi-step adjustment protocol are harder to justify compared to a standard highback booster at $35–80 that provides comparable FMVSS 213 crash protection in a simpler package. CPSTs familiar with the hifold and note the complexity of the adjustment system — while unique — adds steps that standard highbacks do not require. The seat's premium is most defensible when the fold feature is actively used.