SDiD 1212 is a Low Frequency (LF) Radio Frequency Identification (RFID) Secure Digital (SD) Card with embedded 2GB SD memory, designed to plug into any Personal Digital Assistant (PDA), Smartphone or other hand-held device with an SD slot. The SDiD card offers RFID read / write capabilities for portable terminals using industry standard LF technologies. Applications include animal identification, herd management, asset tagging, oilfield logistics and process compliance, vehicle security and fuel payment systems. Transaction or tag data can be processed through mobile wireless connections associated with the portable device or utilized with local application and data store in the embedded 2GB SD memory. Combination of the SDiD 1212 with a network connected handheld device provides a high performance, economical system for mobile LF RFID.