The EM4100 format is a popular Low Frequency (LF) format.  These tags operate at 125kHz and are read-only.  They are pre-programmed with a unique 10-digit ID number in each card.  This number is printed on the cards.

• Pre-programmed with a unique 10-digit ID number in each card (These cards are read-only and not re-writable.) 
• Compatible Formats: EM4100, EM4102, TK4100
• Operation Frequency : 125KHz
• Standard: EM4100
• Ideal for use in ID and access control
• Card Size: 85.60 x 53.98 mm (CR80: standard credit card size)
• Card Thickness: 0.9mm
• Colour: White
• Card Type: Access Card
• Material: PVC Plastic
• Waterproof

EM4100 cards are used for many applications including building access control (home, office, warehouse, car parking), retail memberships, gym memberships (Paxton Net2), photocopiers (including the Fuji Xerox Integrated RFID Card Reader), forklifts, fuel bowsers, payroll bundy clocks and more.