... in double side 3.No need battery EM-01A Thin CardThickness 0.8mm, EM chip,125K RO (Read Only) ... chipEM-01B Thick CardThickness 1.8mm, EM chip,125K RO (Read Only) chipEM-01C Thick CardThickness ... 1.8mm, EM chip,Special card for middle distance card reader.1.Frequency ... 54W x 1.8H(mm)7.Weight: EM-01A:8.5g, EM-01B/C:10.5g8.Standard Packing: 50pcs ...