A number of drivers have voiced their unease at the FIA's "silly" decision to make the use of cooling vests mandatory at 'heat events' from next year.

At present - as is the case this weekend in Singapore - use of the vest at races that have been declared heat events is not mandatory. However, all cars must be fitted with the necessary equipment to power them and those drivers that don't wear them must have a mandatory 5kg in ballast added to their cars.

Speaking at the drivers' briefing on Friday, and again after qualifying, a number of drivers voiced their unease with the ruling.

"I haven't used the vest," said Max Verstappen on Saturday after qualifying. "I'm also not intending to use it because I feel like this needs to be a driver choice.

"Of course, from the FIA side, they will always throw it on safety," he added, "but then we can talk about a lot of stuff that can be improved on safety, including pit entries in certain places. I think that has a bit more priority than a vest in the car because I don't like it.

"I don't like the tubes that are on you, on your body, with the belts that go next to you," he continued. "Then they can say it's just a bad design. I disagree. It just needs to be an option for the drivers to choose.

"Some like it, some don't, and that's fine. But it should be a personal preference. And I know this year we can, but probably next year they don't want to do that, and I feel that is not the right thing.

"The problem is that in GT cars or any other cars, prototypes, you have a bit more space to put stuff or at least put the cables. In our cockpits, it's so narrow that there is no space, or at least not enough space. And that is also a little bit of a problem I find.

"Plus, where are you going to put the dry ice?" he asked. "The cars are not designed really to have this extra kind of space, and within 15, 20 laps, it's anyway gone. And then you have hot water... or tea!"

"I'm happy not to make it mandatory and the ones that don't want to use it have a disadvantage in the race," said Carlos Sainz, the Grand Prix Drivers' Association (GPDA) chairman. "For me it's as simple as that.

"I'm convinced it works and it helps, even though I've done ten Singapores without suffering physically and being able to finish. As soon as you study a bit of physiology you understand that there's a performance advantage," he insisted.

"I think if it's not a huge safety issue they should leave it open," he said of the choice to wear it. "I agree with the guys that don't want to use it. If they don't want to because they feel really uncomfortable then don't use it."

"I don't think it should ever be forced on drivers," agreed Lewis Hamilton. "They keep saying it's a safety issue, but there's no driver that's ever died from overheating in the race, apart from obviously in flames back in the day. It's like, it's just getting silly. That should be our choice to have it.

"I appreciate they've made it available to us and we'll continue to work and improve on the system and I think it can be potentially beneficial in crazy hot places, but if you want to use it because it's comfortable, it should never be like you have to wear this."

Asked if he will wear one this weekend, he replied: "I have tried it, yeah. I might use it tomorrow, depending how hot it is."

"I'll run it," said George Russell, ever the goody-goody. "I ran it in a couple of races this year. It isn't the perfect solution yet.

"The fact is, you have no testing," he continued, "you can only test it in a race environment. The race in Bahrain, I was happy with it. I ran it in Saudi as well. I was happy with it.

"But, of course, here it is much hotter. The dry ice will melt faster. But the team have made big improvements with the car cooling of itself. We recognise some quite major issues of sort of hot air seeping in.

"The cockpit massively exceeded 60C at certain races and just moving a few electronic boxes around and hydraulic lines that are running at 120C around your feet have a major impact on the heat. I'll give you an answer tomorrow..." he smiled.

"I still don't know if I'm going to use it," admitted Oscar Piastri. "I used it yesterday.

"The problem with the suit is it's great when it works. But if it fails, it's even worse than not having it.

"The initiative is good. But, like Max said, having the choice to use it or not is important because there are benefits and downsides."