The indicator light turns red when the USB is connected to the device, and the indicator light turns blue when the card is inserted into the card slot.High-quality socket, can support at least 100,000 card insertion and removal. It supports Microsoft Windows XP and above, Linux Fedora FC8 and MAC OS 10.6.2. It is suitable for notebook computers, Apple notebooks, desktop computers. The smart card reader implements communication with the PC environment through a USB interface compatible with different operating systems.And it can be used for CAC (Common Access Card), Government ID, National ID,etc. Support bank, post office, chip cards issued all over the country. It supports Class A, Class B, and Class C (5V, 3V, and 1.8V) smart cards that comply with the ISO 7816 standard.It has a smart card slot and a SIM card slot, which can be used separately but not simultaneously.It is an easy install USB device fit for all contact smart card operations like online-banking or digital signature applications.