The Sparco RW-4 Long Sleeve Top (part 001782MBI) is FIA 8856-2018 approved race underwear, the current standard for fireproof base layer garments required in most sprint, circuit and rally series that mandate FIA suits. The base layer is not optional in those series: the outer suit alone does not provide adequate thermal protection without approved underwear underneath it.
The long sleeve design protects the arms and wrists where a race suit’s sleeves can ride up during driving, which is a genuine exposure point in a fire. It sits directly against the skin under the race suit and adds a fireproof layer at the point where thermal protection matters most.
The RW-4 sits towards the upper end of Sparco’s underwear range. Compared to entry level options, the construction and materials give better breathability and comfort over long stints. For endurance events or sustained competition in warm conditions that difference is meaningful. Entry level underwear meets the regulatory requirement; the RW-4 makes wearing it more bearable over a full event.
Ultra flat seams, printed rather than stitched logos to keep the weight down, and an X-Cool silver treatment that is anti bacterial and gives a cooling feel against the skin.
Sizes, by chest measurement
Five sizes. S is a 34 to 36 inch chest, which is 86 to 91cm. M is 36 to 38 inches, 91 to 96cm. L is 38 to 40 inches, 96 to 101cm. XL is 40 to 42 inches, 101 to 107cm. XXL is 43 to 45 inches, 109 to 115cm.
Take a tape measure to your chest rather than working from a shirt size. It is meant to fit close, and a loose base layer bunches at the shoulder under a suit and rubs there for the whole stint.
Available in white only. White is standard for race underwear because it is easier to assess an injury through following a fire, and it runs cooler in warm climates than a dark colour.
Sold as a single top. If you need the matching FIA 8856-2018 approved bottoms, the RW-4 long johns are the pair to it.
