HiLetgo 3pcs RFID Kit - Mifare RC522 RF IC Card Sensor Module + S50 Blank Card + Key Ring for Arduino Raspberry Pi

They work as expected. No issues at all. Placed inside an ABS box they easily read mifare cards held about half inch away on the other side (interfaced with an Arduino nano). Well worth the money.

As soon as the tag readers arrived and the pin headers were soldered on, I uploaded the "firmware check" sketch to my Arduino and wired them up one reader at a time, and all three readers passed the initial testing. I then wrote up a quick sketch to provide audible confirmation, and to display tag information on a 20x4 I2C character display. All three cards and all three key fobs scanned with no issues. I do look forward to doing more experiments with these RFID readers and tags. For $10, it was a great value.

Hooked these up to an ESP8266 as a fun project. I intend to make it so these cards can open our garage as we already have a deadbolt lock that can scan cards to unlock. Range seems good and was pretty easy to hook up with a little research on SPI. I do wish they had I2C support out of the box.

Fun and useful device for most microcontrollers. Easy to learn. Good price. Tags and cards, both, work the same.

Useful

Can't go wrong with HiLetgo, their products always perform as advertized, and these modules are no exception. Now as far as the modules themselves, the one limitation I found (using 3.3V) is they need to be really close to the keyfobs, so putting them inside a plastic case adds too much distance as the crystal on top adds an extra 3 or 4mm of space. It would be easier with the antenna trace on the flat bottom side.

Unfortunately none of the 3 cards worked. I tried 3 different raspberry pi's to make sure it wasn't that.

Works and does what it advertises. I used one to build an RFID jukebox.