When to use the top tether strap?

I have seen much confusion around car seats with tether straps, and those without, when to use it, rearward and forward use. So let’s clear this up in this blog post.

Firstly it’s important to remember that New Zealand allows the sale of 3 different countries standard of seat, and as such, each standard has differing requirements in regards to the top tether.

Australian car seats.

Australian standard, AS/NZS 1754

Known here as the Safe N Sound, Mother’s Choice, IGC, Infa Secure, some Safety 1st and Maxi Cosi branded seats.
Australian seats are currently identifiable as seats with height markers on the cover around the shoulder (since 2010-2012), they also have a tether strap that comes out from the top back sides of the car seat. Or a single strap that can be split off, as two straps, found on seats that install rear and forward facing, some forward facing only seats have a single strap these days, such as Maxi cos (the same as our Safety 1st complete Air, without rear facing ability).
These seats require the top tether to be used at all times, in both rear and forward facing positions, the strap must pass to the rear of the car, and in some cars will require an extension strap to reach the bolt if tucked in the far rear of the car.

In short – Always use, to the rear of the car.

 American seats

FMVS 213 – Show a yellow “S” mark (NZ Standard)

They come as bit of a mixed bag these days. The likes of Evenflo, Diono, Britax, Safety 1st, etc. They have a top tether attached and are designed for use forward facing. Some of these seats, Diono RXT, Diono R100 and Britax Boulevard can be used tethered to the front when rear facing attached to a “D” ring. All other American seats sold here need to be used with no tether when installed rear facing. The strap must remain attached to the seat shell, so it does not become a projectile risk.

In short – not required rear facing. Not all seats allow tethering to the front of the car, check your seat manual.

European seats

UK ECE 44.03/44.04.

Some have top tethers, some don’t and some tether to the front seat in front of the car seat, using 2 straps.

Brio Zento, Axkid and Britax Max Way seats use the dual straps to the front seat.
Many other UK seats sold here do not have top tethers at all, they cannot be added either. They rely on a full lap & sash seat belt for the install, wrapping around the back of a capsule (unless used with an in car base), and weaving awkwardly in and around the frame of a forward facing seat, the shoulder strap of the seat belt acts like a tether strap for the seat. Capsules often need the handle to be turned forward when used in the car if not used with a base.

In short – probably not likely to have a top tether, and if it does it typically found on rear facing only seats.


Comparison – Convertible Seats/Boosters

S170 – Safety 1st 70
MXEA – Maxi Rider Easy Adjust
ESK – Evenflo Secure Kid
CSC – Cosco Scenera
ETB – Evenflo Tribute
BSI – Baby Safe Isofix
ES3 – Evenflo Symphony E3
F90 – Frontier 90


Harness slots
CSC- 20, 26, 33 and 38cm
ES3- 18 through to 43cm (infinate)
BSI –  20, 26.5, 34 and 39cm
ETB - 21, 26, 31, 36 cm
ESK – 32, 36, 41, 46 cm
MXEA -  26, 28, 31, 33, 36, 38.5, 40, 43.5 cm
S170 -  22, 28, 32, 38, 42 cm
F90 – 29 – 48 cm

Buckle slots
CSC- 9, 13 and 16 cm
ES3 - 17.5cm
BSI –  17.5cm
ETB- 12, 17 cm
ESK – 13, 18 cm
S170 - 10, 13, 16 cm
F90 – 17, 23.5 cm

Seat width
CSC- 44cm
ES3 – 56cm
BSI –  41cm
ETB – 45cm
ESK – 47.5 cm
MXEA – 44cm
S170 - 45 cm
F90 – 48 cm

Internal width
CSC – 32cm
ES3 – 56cm
BSI - 26cm
ETB – 32cm
ESK – 29cm
MXEA – 37cm
S170 - 32cm

Legs width
CSC – 30 cm
ES3 – 15.3 cm
BSI - 26 cm
ESK – 31 cm
MXEA – 29 cm
S170 - 34 cm
F90 – 30 cm

Bum to top
CSC- 59cm
ES3 - 63cm
BSI - 63.5cm
ETB – 56cm
ESK – 73cm (HR Max setting)
MXEA – 78cm (HR Max setting)
S170 - 69cm (HR Max setting)
F90 – 60 – 79 cm

Bum to legs
CSC - 28cm
ES3 - 33cm
BSI – 33cm
ESK – 29cm
MXEA –  29cm
S170 - 30cm
F90 – 35 cm

Measurements are taken without compressing the fabric (only lightly) and shoulder and leg widths are taken from the middle shoulder slot and approx. 10cm in from the front of the leg area.

Comparing seats

Highest Top Slots
Evenflo Sureride 48cm
Evenflo Securekid 300 46cm
Safe n Sound Maxi Rider Easy Adjust 46cm
Safety 1st Complete Air 44cm
Diono RXT / R100 43cm
Tallest Internal Shell height Includes head rest to the top
Safe n Sound Maxi Rider Easy Adjust 79cm
Evenflo Securekid 300 73cm
Safety 1st Complete Air 69cm
Diono RXT / R100 64cm
Evenflo Sureride 63cm
Weight Limit (Harness)
Diono RXT 36 kg
Safety 1st Complete Air 32 kg
Evenflo Sureride 29 kg
Evenflo Securekid 29 kg
Diono R100 29 kg
Maxi Rider – Unknown Height based | not on the market long enough to get an average

What about my 3-in-1 seat?

In response to our recently posted entry: UK Standard 3-1 boosters, are they safe?

We had a number of parents wondering about their 3-in-1 seat, with detachable back/bottom and the risk their seat may have of detaching in a similar manor to that shown in the video on the link above.

The answer is complicated but we will do our best to explain it to you and allow you to make your mind up about your car seat.

These seats DO meet standard, under UK ECE 44.03 or 44.04.

In the UK there are multiple “Testing Houses”, where you find a crash test sled, electronic equipment and engineers with crash analysis skills. These houses have various companies submitting their seats for testing, some will use the same company for many years.

When a seat is placed on the sled in rear or forward facing orientation they have to pass a “minimum” threshold for a range of different things, including G-force, the distance a seat moves from the sled during an impact, head excursion and so forth.
The minimum however is enough to basically say “the child remained within the seat during the test. The speed at which the test is done is quite low, and cannot reflect what would be the outcome in an open road car-hit-dear type impact.

While the shells are blow moulded, they are designed to take some of the force from the child, some of these seats meet only the minimum standard requirements reflected in the  materials used, the lifespan applied (most of which do not state a duration, but realistically would not exceed 5-6 years). and largely the price applied at the checkout.

They are mass produced, they skim through testing, and when a problem occurs there is no one place to pin point, the seats have no single batch identifier and no original place of manufacture. They are made somewhere in China, and pass through a testing house somewhere in the UK.

If you have your doubts you’re probably right. We cannot (without building our own testing house, and testing each batch of seats as they come in, like they do with seats under NZ S 1754)  test each of these 3 in 1 seats to see what the outcome is. The fact is that as the back is NOT attached to the bottom, rather pressure mounted, with the belt oddly threaded through the seat back, the seat belt retractor above off to one side of the seat, there is a likelihood that the seat back can detach under force.

Unfortunately aside from the video recording, we cannot tell you that your seat is or is not safe, rather that it comes under a parental decision until the likes of NZ Transport Agency pick up on it and investigate it further … we have initiated this process.

–As a addition to this, I do recall seeing a car seat off to the side after an accident (fatal) where a child had one of these seats, the seat was in 2 pieces on the ground next to the car. Though I cannot say for sure if they took it out like this, or if it was viewed by investigators and as part of this detached during their procedure. It was also not clear if the harness was still in the seat or if it was used as booster, the child was of age that a harness was still required.

UK Standard 3-1 boosters, are they safe?

Many parents opt to by a 3-in-1 booster seat primarily because of the price, they’re cheap.

But are parents being misled into buying cheap potential death traps?
Sure they pass standards, but in some cases there is a huge difference between “passing” and “exceeding”. For example, these 3-in-1 boosters, vs. the Diono RXT, one of which “passes”, the other which clearly “exceeds” beyond the minimum.

These are sold in many baby stores, online stores as well as the likes of TradeMe. They’re often under $120, at times creeping down to as low as $69.

They harness to 18kg, and then become a booster seat to be used with a full adult lap/sash seat belt. When used in harness mode the seat belt “weaves” into the rear of the seat from the front, across the back and out the opposite side. They cannot be used with a locking clip as often the seat belt needs to feed over the arm rests, and there is no top tether attached to these seats.

To cut to the chase this is some recently recorded footage of a typical 3-in-1 booster seat sold here in NZ, under multiple brand name, makes and models. This is why we’re not pointing to any one brand in particular.

In the clip below you can see the base and back of the seat detach while the child is in the seat. These seats only “slot” together. When the seat belt locks at the pillar, the seat is pulled up hard to that same side, at enough of a force and angle that it disconnects the seat from itself.

Should these continue to be sold here, and is it time that seats imported from the UK are submitted to Bureau Veritas for certification under New Zealand’s NZS 1754 standard, the same as seats bought over from the United States of America?

Evenflo Tribute vs. Cosco Scenera

This entry is to compare the Evenflo Tribute (Tas Baby) and Cosco Scenera (Dorel Products). These seats are similar in terms of features and price and are often a solution for a lower budget seat.

We will begin by covering the main features of each seat, then the measurements of each and top it off with some photos to show these seats side by side while we still have the Tribute in our collection.

The Cosco Scenera used is dated April 2008, the Evenflo Tribute is dated March 2010. Do not pay attention to these days as such as the seat moulds have not changed so the measurements are still the same and the weight limits listed are based on currently sold seats dated 2012.


Evenflo Tribute: RF 2.3 – 15.8 kg. FF 9-18 kg.
Cosco Scenera: RF 2.3 – 18 kg. FF  9.9-18 kg.
Top Tether: Both used only FF
ISOfix attachments: Both used RF or FF
EPS Foam: Evenflo only – covering head area.


Shoulder slots: 21, 26, 31, 36 cm
Crotch slots: 12, 17 cm
Internal width: 32 cm
External width: 45 cm
Shell height: 65cm
Seated height (bum to top of seat): 56 cm
User height : 48cm – 101 cm

Shoulder slots: 21, 26, 32, 38 cm
Crotch slots:  10, 13, 16.5 cm
Internal width: 35 cm
External width: 45 cm
Shell height: 68cm
Seated height (bum to top of seat): 60 cm
User height: 48 – 110 cm


In addition to above measurements and details…

- Cosco has a slightly higher shell, higher rear facing weight limit, slightly higher slots, 1 more crotch slot, same number of harness slots. Can use all slots for rear facing. Crotch strap is shorter at 13 cm. There is no EPS foam under the cover. Costs $174-$209

- Evenflo has EPS* foam under the cover, claims to be side impact tested* (logo attached to seat), has a longer crotch strap length at 18 cm. Cannot use top slots for rear facing use. Costs $179 – $249

- Both have slots for attaching LATCH and top tether when not in use. Similar thin padding. Have continuous harness (See here for a video on this). Similar flex plastics. Similar overall features and quality.

- Neither come with harness strap covers or buckle pads.

*A note on EPS foam and side impact testing – There is no proof that EPS foam is any safer than no EPS foam, while is it presumed that it plays a part in absorbing energy during an impact given their use in helmets for more than 20+ years. American Standard FMVS 213 (which both of these seats meet, in addition to NZ “S” 1754) does not test or measure side impact testing as part of their standard. However individual companies are opting to test this, though their methods may differ given the fact it is not mandatory in the States.