The ML-525 data loggers are equipped with a soldered, reliable SLC SD card with limited capacity, whereas the 525SE and 525PE models can be fitted with an optional removable SD card, offering virtually unlimited storage for log data.
Although the soldered SD card has limited capacity, its 112 MB ring buffer can retain several years of log data, depending on the requirements of your application. When it becomes full, the oldest data is overwritten to make room for new data
You can use the calculator below to determine whether the capacity of the soldered SD card is sufficient for your application or whether a removable SD card is recommended.