If you are looking for a smart card reader that supports contact based SIM-Sized Smart Cards (contains a single SIM Sized Card Slot or Micro-SIM) with a MicroUSB OTG interface into your mobile phone then the ACS ACR39U-A3 is a good choice. It is small, easily portable and supports most of the mobile devices in the current market that run applications using SIM-sized contact chip smart cards. It therefore supports ISO7816 smart cards, GSM11.11-compliant cards, some memory card support, along with microprocessor cards with T=0 and T=1 protocols. The ACS Mobile Card Reader ACR39U-A3 is PC/SC and CCID compliant and can be easily integrated with a mobile device running either an Android™ platform (from version 3.1) and used in Windows®, Linux®, or Mac OS® platforms.