The IAA-766 is OMP’s One Technical sock, approved to FIA 8856-2018. That approval covers the sock for use in FIA regulated car motorsport where fire resistant legwear is specified, alongside the suit, boots, gloves and balaclava.
25cm high, and that is the point
OMP cut these to 25cm specifically to comply with FIA regulations. The rule is about coverage: the sock has to meet the leg of the suit with no gap of bare skin between them, because that gap is exactly where a burn happens.
So a shorter fire retardant sock is not a cheaper version of this, it is a sock that does not comply. If you are being scrutineered, the height matters as much as the standard printed on the label.
Construction
The construction uses differentiated pressure zones across the sole and ankle, which affects blood circulation during extended seated use. The practical result is reduced leg fatigue over a long stint, the kind of benefit that matters in an endurance event rather than a five minute sprint. The fabric is breathable to keep foot temperature down when wearing boots in a hot cockpit.
Available in black or white, sizes S, M and L. All carry the same FIA 8856-2018 approval.
Building the set
For anyone putting together a complete OMP fire kit using the First range, these pair with the First race boot and the First overall, all three to FIA 8856-2018. They also work in karting where the event regulations call for technical fire protection socks.
These are not everyday socks. The FIA approval requires the materials to perform under specific conditions, and regular machine washing in standard detergent degrades that performance. Wash to the manufacturer’s care instructions.
Have you written anything about this exact product?
Yes, we have covered this exact product: The OMP One Evo X Set: Suit, One Evo X Boots And One Evo X Gloves, and OMP One Evo FX Race Boots 2026 – The Latest Evolution in Motorsport Footwear. That is first-hand coverage from our own builds and showroom, not brochure copy.
Do I actually need FIA underwear?
If your championship requires it, this is the layer scrutineers ask about, and it is strongly recommended under any suit regardless. These socks are homologated to FIA 8856-2018, the current FIA standard, so the label is there when scrutineers ask for it. Our guide on whether fireproof underwear is mandatory covers the rules championship by championship.
What size should I go for?
Sizes run from S to L. Underwear layers should sit close to the skin without pinching, as loose fabric wrinkles under the suit and gets uncomfortable fast. Between sizes, take the smaller one for a base layer.
How do I wash it?
Underwear layers are the one bit of racewear you should wash after every use: cool and gentle, no bleach or fabric softener, air dry. That keeps the suit itself needing far fewer washes. Full routine in our racewear care guide.
At GSM Performance, our priority is to maintain the utmost hygiene and quality standards for the benefit of our customers. To that end, we have instituted a policy that all purchases of long johns, balaclavas, tops, and underwear are final and non-returnable. This policy is necessary due to the personal nature of these items, which are worn in close contact with the body. This protocol is intended to guarantee the health and safety of all our customers.
This policy adheres to the best industry practices and safeguards both our customers and our staff. It's important to clarify that this policy does not affect your statutory rights as a consumer. This policy does not apply if you receive damaged or defective products. In such cases, our customer service team is available to promptly address your concerns and arrange a replacement or refund. We greatly appreciate your understanding and adherence to our hygiene policy and thank you for your continued confidence in GSM Performance. For further information please see our terms and conditions which are agreed on checkout.
