ST16 has an internal memory of 5gb. Inserting micro SD card on bottom of ST16 will allow you to copy telemetry data to external memory if needed. Press pad icon Click ok Pad icon to continue File manager Flight log Telemetry Files By pressing down arrow icon you may copy, cut, delete etc. Copy and tap on SD card icon on upper left hand corner to access external card. Paste file to external SD card. Telemetry file now appears on external memory and may be viewed on your PC.