More criticisms have been levied against the head protection device formerly known as the 'Halo'.
The head protection is set to be introduced in 2018 after drivers called for its planned 2017 introduction to be shelved.
Now a number of drivers are again speaking out against the device.
"It almost made me sick. I felt something like claustrophobia," Haas driver Romain Grosjean is quoted by Auto Motor und Sport.
2017 Renault driver Nico Hulkenberg added: "It restricts the view, especially when many corners follow in a sequence like in Singapore.
"I think the FIA delayed the introduction for good reason," the German said.
Hulkenberg's team mate for next year, Jolyon Palmer, agrees: "In a fire, I'd prefer not to have a Halo over the cockpit."
"I think we have to wait to be turned back over. We have complained about that," he revealed.
Hulkenberg, one of the tallest drivers on the grid, agreed, saying: "I can barely meet the 10 second procedure" for getting out of the car and replacing the steering wheel.
Sauber's Marcus Ericsson said: "It was hard for me to get out."
Palmer meanwhile has questioned the need for such a device at all, insisting that F1 is safer than it one was.
"With the large run-off zones, Formula One is no longer as dangerous as it used to be," Palmer insisted.
Bahrain International Circuit - Winter testing
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