Holmbergs RollFix™
Making car rides safer for kids

You could have the safest car seat in the world, but if your child isn’t buckled in correctly, it could still be deadly. And the biggest danger for children in car seats is having too much slack in the harness straps.

Why slack matters

When your car seat’s harness straps have slack in them, it can result in serious injuries, as the child will feel the force of a hard brake or crash much more than if the straps were tightened properly.

Straps that are secured properly hold your child snugly in their seat, lessening the force of a crash.

Almost half of all children in cars are in danger

Thirty-five percent of children killed in car crashes in 2018 in the United States were unrestrained1.

Clearly child car seats make a difference.

But, even if someone is using a child car seat, if it’s not used properly, it puts children at risk.

Unfortunately, many people are not using their car seats properly. An estimated 46% of child car seats in the USA are not used correctly2, meaning the protection they usually provide in a crash is reduced.

How improperly secured straps harm children

1. If a harness is looser on one side than the other, the forces of a crash are distributed unevenly across a child’s body, increasing the risk of injury.

2. If the harness is twisted, it might disrupt the seat’s strap locking mechanism and also concentrate more force over the narrower, twisted area, intensifying the impact of a crash.

3. If the harness is not tightened enough, the child might be able to climb out of the car seat or be ejected from the seat.

4. If the child is wearing bulky clothes, the harness will most likely not be able to secure them. It’s always better to remove oversized attire before buckling the child into the seat.  

5. If the strap height is incorrect, it can affect how much the child’s body is able to move during a crash. It’s crucial to adjust the height of the harness according to the owner’s manual as your child grows.

Properly secured car seats work

Correctly used child safety seats can reduce the risk of death by as much as 71 percent3.

That’s a huge reason to make sure you are securing your child correctly.

But, we get it.

When you’re a new parent and you’ve never buckled a squirming child into a car seat before, it can be daunting. You don’t want to accidentally hurt them or make the ride uncomfortable for them.

So, you leave a little bit of slack.

Or, maybe you’re in a hurry because your child is cranky and you just want to get the car moving so they’ll sleep. Perhaps you aren’t even sure how to tighten the straps because some car seats have multiple buckles and straps.

Worry no more…

Holmbergs RollFixTM

Holmbergs aims to make transportation safer for everyone. Since too much slack in child car seat harness straps is a worldwide problem, we had to solve it, like a world leader in safety should.

That’s why we invented Holmbergs RollFixTM, the slack reduction system.

How does it work?

Holmbergs RollFixTM uses two specially-designed, spring-loaded retractors that are embedded in the back of the car seat, meaning a seat with Holmbergs RollFixTM has just one buckle and two straps.

When the buckle is unbuckled and in the downward position, the straps can move freely in both directions. When buckled and in the upright position, the straps can only be tightened.

To tighten the straps, parents feed the straps through the two slots in the back of the seat above the child’s shoulders.

The Holmbergs RollFixTM retractors emit a clicking noise when the straps are tightened. Once the clicking noise stops and the straps cannot be fed anymore into the back of the seat, they are secure.

Additionally, the spring-loaded mechanism in the retractors gently and continuously pulls on the straps during the ride, preventing slack.

Once the harness is unbuckled and the buckle is in the downward position, the straps can be loosened.

With Holmbergs RollFix™, the problem of too much slack is a problem of the past.

For more information, read about Holmbergs RollFix™ here: RollFix™ – Holmbergs


  1. 2018 Data: Children (dot.gov)
  2. How to Properly Adjust Your Car Seat Harness – Consumer Reports
  3. Car Seat Safety Tips | Safe Kids Worldwide