Sergio Perez has raised concerns about the amount of extra time it takes to climb out of an F1 car that has Halo attached, saying it makes him "feel a bit uncomfortable."
The Mexican racer ran Halo for the first time on Friday morning, putting in a brief run at the Monza circuit.
But while Perez was happy with the visibility Halo permitted, he is worried about the added time it takes to get out of the car.
"Visibility wise it was quite good, that surprised me," he said. "But my concern is how slow you get out of the car.
"It takes a good five seconds more than without the Halo.
"So it is something that makes me feel a bit uncomfortable – knowing that I need more time to get out of the car than without it.
"I still think there is more work to be done. For example, in that area to try to get us drivers out as quick as possible compared to the non-Halo getting out of car.
"You are sitting in a car and you know that it is going to take you five seconds longer already than without the Halo.
"If you are in a critical situation, five seconds can be a lot."