SFI 3.3 covers the equipment a driver wears with the suit. Gloves are graded like suits. Underwear, hoods and socks have a single minimum, and so do shoes and boots.
What the specification covers
SFI 3.3 sets minimum standards for driver accessories. As with 3.2A, certification is made by the manufacturer under licence, and products are not certified, endorsed or approved by SFI.
Underclothing must cover the body from neck to ankles and wrists and fit snugly at those openings. Hoods need a bib reaching at least 6 inches (15.2 cm) below the chin. Socks should overlap the underwear or suit.
Gloves
Each finger and thumb must have its own section. A glove is graded by the TPP of its top covering. For grades above /1, the palm side must reach at least 40% of the top's required TPP and the forchettes (finger sides) at least 20%, or grade 1 if that is higher. A glove that misses those values is downgraded until every section conforms.
Leather palms are allowed, but the palm and forchettes may not be leather alone: a layer the manufacturer represents as fire-resistant must separate the leather from the hand.
Glove seams have their own flammability test.
| SFI grade | Top | Palm side | Forchettes |
|---|---|---|---|
| 3.3/1 | > 6 | n/a | n/a |
| 3.3/5 | ≥ 19 | ≥ 7.6 | ≥ 6.0 |
| 3.3/10 | ≥ 38 | ≥ 15.2 | ≥ 7.6 |
| 3.3/15 | ≥ 60 | ≥ 24.0 | ≥ 12.0 |
| 3.3/20 | ≥ 80 | ≥ 32.0 | ≥ 16.0 |
| 3.3/25 | ≥ 100 | ≥ 40.0 | ≥ 20.0 |
| 3.3/30 | ≥ 120 | ≥ 48.0 | ≥ 24.0 |
SFI 3.3 Table 1: glove TPP per grade (cal/cm²).
Underwear, hoods, socks and shoes
Underclothing, hoods, socks, helmet supports, harness pads and sports bras must reach a minimum TPP of 6.0 cal/cm².
Shoes and boots must use fire-resistant material in the non-sole area and reach a minimum TPP of 19.0 cal/cm².
Fabric layers must average 2.0 seconds or less of after-flame and 6 inches or less of char length, with no melting or dripping.
Marking
Every individual item carries its own patch: on each glove at the upper cuff (or visibly inside it), on the left sleeve or shirt hem of underwear tops, at the left belt line of pants, on the lower front bib of hoods, above the ankle on each sock, and on the upper outside or visibly inside each shoe.
What buyers should check
- Check that each glove, sock and shoe carries its own patch, not only the packaging.
- For gloves, confirm the grade covers the whole glove, not only the back of the hand.
- Check that the certifying manufacturer appears on SFI's published 3.3 manufacturers list.
- Check the minimums your series sets for gloves and shoes, which can be higher than /5.
Sources
Read from the official documents on 8 November 2026. Standards are revised, so always check the current edition and the rules of your series.