There's one question we get a lot; it has to do with belt aging. Specifically, if a belt has an SFI certification label with a manufacture date and an FIA certification label with an expiration date, which takes precedence?
Short answer: the FIA label takes precedence, which is a good thing, because SFI based expirations are now 2 years in most sanctioning bodies, and FIA belts, while more expensive, are generally good for at least twice as long.
Why is this? Because the SFI permits belt webbing to be made from shorter lived materials which the FIA does not accept (I'll post a follow up on this materials question later.)
Here is a helpful hint for anyone who has just bought or is about to buy belts: as soon as they arrive, open the box and check the date on the SFI label. It should be within a month or two (or maybe three) of the day you open the box. Don't be suprised if the date hasn't arrived yet; sometimes vendors post date towards an expected date of sale. If it's more than a couple of months old, though, call the vendor you got them from and give them an earful (and get a newer set of belts out of them). With non-FIA belts, the SFI date of manufacture defines when you will have to toss them and get a new set.