A type of memory card that was popular in the past. Memory cards are based on Flash memory and are used as solid state storage, their main purpose being an inexpensive way to store or transfer data between computers and other digital products. RS-MMC are based on the MMC standard and share their form-factor and size with MMCmobile cards. The difference between the two formats is that MMCmobile cards are dual-voltage and can operate in older phones with a high-voltage (3V) slot as well as in newer models with a low-voltage (1.8V) slot. Traditional RS-MMC cards can only work in devices with a high-voltage (3V) slot.