Do RFID blocking wallets do anything?
They work, and completely: a conductive layer stops a card being read at all. Whether that is worth buying is a separate question, because the attack it prevents needs sustained proximity and an accredited terminal, and it also stops every other card and tag you carry.
They do work
A conductive layer around a card prevents the reader's field from reaching it, and the card is then inert rather than weakened.
This is not a marketing claim that fails on inspection. The physics is straightforward and the effect is total.
The same effect is produced free by a metal card, a money clip or a coin sitting against the card, which is worth knowing before buying anything.
The threat they address
Somebody bringing a reader within a couple of centimetres of your wallet and holding it there while an exchange completes.
That is a smaller threat than the marketing implies, for reasons covered elsewhere on this site: the proximity required is close and sustained, and the exchange obtained cannot be turned into money without accreditation.
It does nothing about a lost card, a merchant dispute, details taken from a breach, or an account takeover, which between them account for the losses people actually suffer.
So the honest description is a working solution to the least likely of the risks.
What they cost you
Every card and tag in the wallet, indiscriminately. A blocking wallet does not know which card you wanted protected.
So a transport card, a building badge, a hotel key or an NFC tag you carry stops working while it is inside, and the wallet has to be opened for each of them.
That inconvenience is why blocking wallets are frequently bought and then abandoned, which is the outcome to anticipate rather than discover.
If you carry a tag you intend to use, a blocking wallet is the wrong place for it, and this is a common and puzzling failure until the cause is known.
Deciding for yourself
Ask what you would lose in the scenario it prevents, and compare it against the daily friction of opening the wallet for a transport card.
Note that a card left inside a blocking wallet is also protected from the payments you want to make, which is either a feature or a nuisance depending on how you pay.
And if the motivation is a general unease rather than a specific scenario, the money is better spent on nothing at all, with the effort going into reading statements.
A single metal card in the stack achieves most of the effect for nothing, if you decide you want it.
Frequently asked questions
Do blocking wallets actually work?
Yes, completely. A conductive layer stops the field reaching the card, so the card is inert rather than merely harder to read.
Is the threat worth protecting against?
It is the smallest of the payment risks. A lost card, a disputed charge and details from a breach are all more likely.
Will it stop my other cards?
Yes, all of them, and any NFC tag you carry. That indiscriminate effect is why they get abandoned.
Is there a free equivalent?
A metal card or a coin against the card produces much the same effect, which is worth trying before buying.