Cisco MEM-1900-1GB= memory module 1 x 1 GB DRAM

The Cisco 1921 ISRs are offered in a fixed-memory configuration, whereas the Cisco 1941 ISRs are offered in an expandable memory configuration. Cisco 1921 ISRs support an internal 256-MB embedded USB (eUSB) flash and an internal soldered 512-MB DRAM memory. On Cisco 1941 and 1941W routers, the default DRAM of 512 MB is also soldered onto the motherboard. Memory upgrades on the Cisco 1941 are available as modular DIMMs in densities of 512 MB, 1 GB, and 2 GB.