diff --git a/documentation/developers/rfid/mfrc522_spi.md b/documentation/developers/rfid/mfrc522_spi.md
index 363df3836..be3abeaa8 100644
--- a/documentation/developers/rfid/mfrc522_spi.md
+++ b/documentation/developers/rfid/mfrc522_spi.md
@@ -78,3 +78,7 @@ MISO.
 MFRC522 boards can be picked up from many places for little money.
 
 Good quality ones can be found e.g. here
+
+### Cards/Tags
+
+Cards or tags must support 13.56 MHz. Currently, only cards/tags of the type "NXP Mifare Classic 1k(S50)", "NXP Mifare Classic 4k(S70)" and "NXP Mifare Ultralight (C)" can be used. Type "NXP Mifare NTAG2xx" or others will not work!