The Plugable TBT4-UDZ docking station has two media card reader slots located on the front of the unit.The first slot is for full-size Secure Digital (SD) media cards.  The second slot is for microSD media cards.Media cards can be inserted into both slots, and both can be used simultaneously. Full-size SD card slotThe full-size SD card slot is a ‘manual’ slot.  When the docking station is in the horizontal position, you simply insert the full-size SD card into the slot with the SD card label facing upwards. Continue to push the card into the dock until the card stops. To remove the full-size SD card, simply pull to remove the card from the slot. *** Please note, prior to removing the card from the slot you may have to manually ‘eject’ the media card from within the host operating system. ***Full-size SD card outside of the docking stationFull-size SD card partially inserted into the full-size SD card slotFull-size SD card fully inserted into the full-size SD card slotmicroSD card slotThe microSD card slot is a ‘spring loaded’ slot. When the docking station is in the horizontal position, you simply insert the microSD card into the slot with the SD card label facing downwards until you hear a ‘click’. To remove the microSD card, simply press on the visible edge of the card with your finger nail and then release. A spring inside the slot will gently push the card outward. Once the card has been released, continue to remove the card from the slot.*** Please note, prior to removing the card from the slot you may have to manually ‘eject’ the media card from within the host operating system. ***MicroSD card outside of the docking station, label facing upwardsMicroSD card outside of the docking station, label facing downwardsMicroSD card partially inserted into the microSD card slotMicroSD card fully inserted into the microSD card slot