S31 is a MSR card reader accessory which attached to our X3 series PDA. This product special designed for retail/logoistics use. Features:Magnetic card type: ISO7811, three trackRFID band: 13.56MHzRFID type: ISO14443 type ARFID card surpport : Mifare 1 (S50, S70), UltrLight, Desfire.... PSAM card type: ISO7816,3.3V S31 MSR(Magnetic Striple Reader)