Do you have a credit card with RFID protector? It’ll show the little Wi-Fi symbol on the card. If not, you are wasting your money completely. The other cards mentioned that use RFID are useless to thieves even if they could steal your data, including your passport.
If you do happen to have an RFID credit card, know that stealing the data is extremely difficult and rare. Yes the companies that sell sleeves and blockers show someone holding a reader next to your ass, but the equipment has to be extremely sophisticated and the criminal enterprise highly resourceful to actually break the encryption and make use of the data. Your average thief is neither of those. Know that people the world over have the RFID card and there is no huge security fraud with them. Your old fashioned magnetic strip credit card is a multitude times more vulnerable to fraud than an RFID card. Your brand new chip and signature card is far more susceptible to fraud than an RFID card will be. So ask yourself is the cost to protect yourself from something with such little risk is really worth it? Do you really need RFID protector?
The RFID sleeve / no sleeve issue reminds one of a plate of spaghetti because it is really hard to determine where accurate information begins and ends. The only thing I can state with certainty is that we recently obtained an credit card with a chip and a pin. (Chip & Pin verses Chip & Signature is another issue altogether). The card issuer provided an RFID sleeve with the admonishment to always keep it in the sleeve when not using it. So why not use it? Practically no weight to it and the sleeve (with the card inside) still fits into the plastic card holder of the wallet. Even if one has to buy half a dozen they don’t cost that much compared to what we really spend on travel.
To repeat a comment I know I’ve made before -“RFID protector” (or whatever else the snake oil salesmen call them) are a solution looking for a problem.