Waspmote Plug & Sense! has an internal SD (Secure Digital) card. FAT32 file system is used and cards up to 16 GB are supported. These cards need the bootloader #J to work properly.
To get an idea of the capacity of information that can be stored in a 16 GB card, simply divide its size by the average for what a sensor frame in Waspmote usually occupies (approx. 100 bytes):
16 GB/100 B = 160 million measurements
The limit in files and directories creation per level is 256 files per directory and up to 256 sub-directories in each directory. There is no limit in the number of nested levels.
The SD card is also used to store the firmware image when performing Over the Air Programming (OTAP).
All information about their programming and operation can be found in the SD Card Programming Guide.