While a conventional backless booster seat elevates your child to fit the adult seat belt, the RideSafer travel vest brings the adult seat belt down to fit your child. One of the great safety features of the RideSafer travel vest is that it allows your child to maintain a lower centre of gravity compared to a conventional booster seat, which can reduce the severity of whiplash injuries in an accident. Using a conventional booster seat would reverse this feature.
2. It hasn't been crash tested
The RideSafer vest has been crash tested and certified as a harness restraint under the American FMVSS-213 standard. It has not been designed nor crash tested to be used in conjunction with a third party booster seat. Conversely, the third party booster seat also hasn't been designed nor crash tested to be used in conjunction with a RideSafer vest.
3. The booster may interfere with the operation of the vest
The RideSafer vest uses metal seat belt guides to appropriately position the adult seat belt across your child's body. Using a third party booster seat at the same time may skew the position of the adult seat belt - this can have three significant implications:
(i) it may change the position of the seat belt relative to your child's body which may inhibit the vest from properly protecting your child in an accident,
(ii) it may cause the seat belt to twist or fold which can localise crash forces onto that part of your child's body,
(iii) it may increase the risk of the seat belt slipping out of the seat belt guides.
4. It breaches the manufacturer's guidelines which may void any warranty/liability
In most cases, using a safety device against the manufacturer's guidelines will void any warranty and increase your liability in the event of an accident. This would apply to both the RideSafer vest and the backless booster.
For parents who want to elevate their children...
... perhaps to see out the vehicle window, the RideSafer manufacturer has designed a compatible backless booster seat which can be used in conjunction with the RideSafer Delight vest. The RideSafer Delighter booster seat has been certified to US crash test standards FMVSS-213 and is the only backless booster seat which can be safely used in conjunction with the RideSafer Delight vest.